* [PATCH 2/3] posix: execvpe cleanup
2016-02-26 13:57 [PATCH 0/3] posix: Execute file function fixes Adhemerval Zanella
2016-02-26 13:57 ` [PATCH 3/3] posix: New Linux posix_spawn{p} implementation Adhemerval Zanella
@ 2016-02-26 13:57 ` Adhemerval Zanella
2016-02-26 19:40 ` Paul Eggert
2016-02-26 14:19 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
2 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 13:57 UTC (permalink / raw)
To: libc-alpha
This patch removes all the dynamic allocation on execvpe code and
instead use direct stack allocation. This is QoI approach to make
it possible use in scenarios where memory is shared with parent
(vfork or clone with CLONE_VM).
For default process spawn (script file without a shebang), stack
allocation is bounded by NAME_MAX plus PATH_MAX plus 1. Large
file arguments returns an error (ENAMETOOLONG). This differs than
current GLIBC pratice in general, but it used to limit stack
allocation for large inputs. Also, path in PATH environment variable
larger than PATH_MAX are ignored.
The shell direct execution exeception, where execve returns ENOEXEC,
might requires a large stack allocation due large input argument list.
Tested on i686, x86_64, powerpc64le, and aarch64.
* posix/execvpe.c (__execvpe): Remove dynamic allocation.
* posix/Makefile (tests): Add tst-execvpe{1,2,3,4,5,6}.
* posix/tst-execvp1.c (do_test): Use a macro to call execvp.
* posix/tst-execvp2.c (do_test): Likewise.
* posix/tst-execvp3.c (do_test): Likewise.
* posix/tst-execvp4.c (do_test): Likewise.
* posix/tst-execvpe1.c: New file.
* posix/tst-execvpe2.c: Likewise.
* posix/tst-execvpe3.c: Likewise.
* posix/tst-execvpe4.c: Likewise.
* posix/tst-execvpe5.c: Likewise.
* posix/tst-execvpe6.c: Likewise.
---
posix/Makefile | 3 +
posix/execvpe.c | 244 +++++++++++++++++++++------------------------------
posix/tst-execvp1.c | 6 +-
posix/tst-execvp2.c | 5 +-
posix/tst-execvp3.c | 5 +-
posix/tst-execvp4.c | 6 +-
posix/tst-execvpe1.c | 20 +++++
posix/tst-execvpe2.c | 20 +++++
posix/tst-execvpe3.c | 20 +++++
posix/tst-execvpe4.c | 20 +++++
posix/tst-execvpe5.c | 157 +++++++++++++++++++++++++++++++++
posix/tst-execvpe6.c | 82 +++++++++++++++++
13 files changed, 455 insertions(+), 146 deletions(-)
create mode 100644 posix/tst-execvpe1.c
create mode 100644 posix/tst-execvpe2.c
create mode 100644 posix/tst-execvpe3.c
create mode 100644 posix/tst-execvpe4.c
create mode 100644 posix/tst-execvpe5.c
create mode 100644 posix/tst-execvpe6.c
diff --git a/posix/Makefile b/posix/Makefile
index 55f4f31..a2aabcc 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -82,6 +82,8 @@ tests := tstgetopt testfnm runtests runptests \
tst-execv1 tst-execv2 tst-execl1 tst-execl2 \
tst-execve1 tst-execve2 tst-execle1 tst-execle2 \
tst-execvp3 tst-execvp4 tst-rfc3484 tst-rfc3484-2 \
+ tst-execvpe1 tst-execvpe2 tst-execvpe3 tst-execvpe4 \
+ tst-execvpe5 tst-execvpe6 \
tst-rfc3484-3 \
tst-getaddrinfo3 tst-fnmatch2 tst-cpucount tst-cpuset \
bug-getopt1 bug-getopt2 bug-getopt3 bug-getopt4 \
@@ -229,6 +231,7 @@ tstgetopt-ARGS = -a -b -cfoobar --required foobar --optional=bazbug \
tst-exec-ARGS = -- $(host-test-program-cmd)
tst-exec-static-ARGS = $(tst-exec-ARGS)
+tst-execvpe5-ARGS = -- $(host-test-program-cmd)
tst-spawn-ARGS = -- $(host-test-program-cmd)
tst-spawn-static-ARGS = $(tst-spawn-ARGS)
tst-dir-ARGS = `pwd` `cd $(common-objdir)/$(subdir); pwd` `cd $(common-objdir); pwd` $(objpfx)tst-dir
diff --git a/posix/execvpe.c b/posix/execvpe.c
index 61697a7..b945ef2 100644
--- a/posix/execvpe.c
+++ b/posix/execvpe.c
@@ -15,7 +15,6 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <alloca.h>
#include <unistd.h>
#include <stdarg.h>
#include <stdbool.h>
@@ -23,15 +22,34 @@
#include <string.h>
#include <errno.h>
#include <paths.h>
+#include <confstr.h>
+#include <sys/param.h>
+#ifndef PATH_MAX
+# ifdef MAXPATHLEN
+# define PATH_MAX MAXPATHLEN
+# else
+# define PATH_MAX 1024
+# endif
+#endif
/* The file is accessible but it is not an executable file. Invoke
the shell to interpret it as a script. */
static void
-internal_function
-scripts_argv (const char *file, char *const argv[], int argc, char **new_argv)
+maybe_script_execute (const char *file, char *const argv[], char *const envp[])
{
+ int argc = 0;
+ while (argv[argc++] != NULL)
+ {
+ if (argc == INT_MAX)
+ {
+ errno = E2BIG;
+ return;
+ }
+ }
+
/* Construct an argument list for the shell. */
+ char *new_argv[argc];
new_argv[0] = (char *) _PATH_BSHELL;
new_argv[1] = (char *) file;
while (argc > 1)
@@ -39,6 +57,9 @@ scripts_argv (const char *file, char *const argv[], int argc, char **new_argv)
new_argv[argc] = argv[argc - 1];
--argc;
}
+
+ /* Execute the shell. */
+ __execve (new_argv[0], new_argv, envp);
}
@@ -47,170 +68,109 @@ scripts_argv (const char *file, char *const argv[], int argc, char **new_argv)
int
__execvpe (const char *file, char *const argv[], char *const envp[])
{
+ /* We check the simple case first. */
if (*file == '\0')
{
- /* We check the simple case first. */
__set_errno (ENOENT);
return -1;
}
+ /* Don't search when it contains a slash. */
if (strchr (file, '/') != NULL)
{
- /* Don't search when it contains a slash. */
__execve (file, argv, envp);
if (errno == ENOEXEC)
- {
- /* Count the arguments. */
- int argc = 0;
- while (argv[argc++])
- ;
- size_t len = (argc + 1) * sizeof (char *);
- char **script_argv;
- void *ptr = NULL;
- if (__libc_use_alloca (len))
- script_argv = alloca (len);
- else
- script_argv = ptr = malloc (len);
-
- if (script_argv != NULL)
- {
- scripts_argv (file, argv, argc, script_argv);
- __execve (script_argv[0], script_argv, envp);
-
- free (ptr);
- }
- }
+ maybe_script_execute (file, argv, envp);
+
+ return -1;
}
- else
+
+ const char *path = getenv ("PATH");
+ if (!path)
+ path = CS_PATH;
+ /* Although GLIBC does not enforce NAME_MAX, we set it as the maximum
+ size to avoid unbounded stack allocation. Same applies for
+ PATH_MAX. */
+ size_t file_len = __strnlen (file, NAME_MAX + 1);
+ size_t path_len = __strnlen (path, PATH_MAX - 1) + 1;
+
+ if ((file_len > NAME_MAX)
+ || !__libc_alloca_cutoff (path_len + file_len + 1))
{
- size_t pathlen;
- size_t alloclen = 0;
- char *path = getenv ("PATH");
- if (path == NULL)
- {
- pathlen = confstr (_CS_PATH, (char *) NULL, 0);
- alloclen = pathlen + 1;
- }
- else
- pathlen = strlen (path);
+ errno = ENAMETOOLONG;
+ return -1;
+ }
- size_t len = strlen (file) + 1;
- alloclen += pathlen + len + 1;
+ const char *subp;
+ bool got_eacces = false;
+ for (const char *p = path; ; p = subp)
+ {
+ char buffer[path_len + file_len + 1];
- char *name;
- char *path_malloc = NULL;
- if (__libc_use_alloca (alloclen))
- name = alloca (alloclen);
- else
- {
- path_malloc = name = malloc (alloclen);
- if (name == NULL)
- return -1;
- }
+ subp = __strchrnul (p, ':');
- if (path == NULL)
+ /* PATH is larger than PATH_MAX and thus potentially larger than
+ the stack allocation. */
+ if (subp - p >= path_len)
{
- /* There is no `PATH' in the environment.
- The default search path is the current directory
- followed by the path `confstr' returns for `_CS_PATH'. */
- path = name + pathlen + len + 1;
- path[0] = ':';
- (void) confstr (_CS_PATH, path + 1, pathlen);
+ /* If there is only one path, bail out. */
+ if (*subp == '\0')
+ break;
+ /* Otherwise skip to next one. */
+ continue;
}
- /* Copy the file name at the top. */
- name = (char *) memcpy (name + pathlen + 1, file, len);
- /* And add the slash. */
- *--name = '/';
+ /* Set current path considered plus a '/'. */
+ memcpy (buffer, p, subp - p);
+ buffer[subp - p] = '/';
+ /* And the file to execute. */
+ memcpy (buffer + (subp - p) + !!(subp > p), file, file_len + 1);
+
+ __execve (buffer, argv, envp);
- char **script_argv = NULL;
- void *script_argv_malloc = NULL;
- bool got_eacces = false;
- char *p = path;
- do
+ if (errno == ENOEXEC)
+ maybe_script_execute (buffer, argv, envp);
+
+ switch (errno)
{
- char *startp;
-
- path = p;
- p = __strchrnul (path, ':');
-
- if (p == path)
- /* Two adjacent colons, or a colon at the beginning or the end
- of `PATH' means to search the current directory. */
- startp = name + 1;
- else
- startp = (char *) memcpy (name - (p - path), path, p - path);
-
- /* Try to execute this name. If it works, execve will not return. */
- __execve (startp, argv, envp);
-
- if (errno == ENOEXEC)
- {
- if (script_argv == NULL)
- {
- /* Count the arguments. */
- int argc = 0;
- while (argv[argc++])
- ;
- size_t arglen = (argc + 1) * sizeof (char *);
- if (__libc_use_alloca (alloclen + arglen))
- script_argv = alloca (arglen);
- else
- script_argv = script_argv_malloc = malloc (arglen);
- if (script_argv == NULL)
- {
- /* A possible EACCES error is not as important as
- the ENOMEM. */
- got_eacces = false;
- break;
- }
- scripts_argv (startp, argv, argc, script_argv);
- }
-
- __execve (script_argv[0], script_argv, envp);
- }
-
- switch (errno)
- {
- case EACCES:
- /* Record the we got a `Permission denied' error. If we end
- up finding no executable we can use, we want to diagnose
- that we did find one but were denied access. */
- got_eacces = true;
- case ENOENT:
- case ESTALE:
- case ENOTDIR:
- /* Those errors indicate the file is missing or not executable
- by us, in which case we want to just try the next path
- directory. */
- case ENODEV:
- case ETIMEDOUT:
- /* Some strange filesystems like AFS return even
- stranger error numbers. They cannot reasonably mean
- anything else so ignore those, too. */
- break;
-
- default:
- /* Some other error means we found an executable file, but
- something went wrong executing it; return the error to our
- caller. */
- return -1;
- }
+ case EACCES:
+ /* Record the we got a 'Permission denied' error. If we end
+ up finding no executable we can use, we want to diagnose
+ that we did find one but were denied access. */
+ got_eacces = true;
+ case ENOENT:
+ case ESTALE:
+ case ENOTDIR:
+ /* Those errors indicate the file is missing or not executable
+ by us, in which case we want to just try the next path
+ directory. */
+ case ENODEV:
+ case ETIMEDOUT:
+ /* Some strange filesystems like AFS return even
+ stranger error numbers. They cannot reasonably mean
+ anything else so ignore those, too. */
+ break;
+
+ default:
+ /* Some other error means we found an executable file, but
+ something went wrong executing it; return the error to our
+ caller. */
+ return -1;
}
- while (*p++ != '\0');
-
- /* We tried every element and none of them worked. */
- if (got_eacces)
- /* At least one failure was due to permissions, so report that
- error. */
- __set_errno (EACCES);
- free (script_argv_malloc);
- free (path_malloc);
+ if (*subp++ == '\0')
+ break;
}
- /* Return the error from the last attempt (probably ENOENT). */
+ /* We tried every element and none of them worked. */
+ if (got_eacces)
+ /* At least one failure was due to permissions, so report that
+ error. */
+ __set_errno (EACCES);
+
return -1;
+
}
+
weak_alias (__execvpe, execvpe)
diff --git a/posix/tst-execvp1.c b/posix/tst-execvp1.c
index ecc673d..fe98ce5 100644
--- a/posix/tst-execvp1.c
+++ b/posix/tst-execvp1.c
@@ -3,6 +3,10 @@
#include <stdlib.h>
#include <unistd.h>
+#ifndef EXECVP
+# define EXECVP(__file, __argv) execvp (__file, __argv)
+#endif
+
static int
do_test (void)
{
@@ -19,7 +23,7 @@ do_test (void)
char *argv[] = { (char *) "does-not-exist", NULL };
errno = 0;
- execvp (argv[0], argv);
+ EXECVP (argv[0], argv);
if (errno != ENOENT)
{
diff --git a/posix/tst-execvp2.c b/posix/tst-execvp2.c
index 7e0f5d8..9be8733 100644
--- a/posix/tst-execvp2.c
+++ b/posix/tst-execvp2.c
@@ -14,6 +14,9 @@ static int do_test (void);
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
+#ifndef EXECVP
+# define EXECVP(__file, __argv) execvp (__file, __argv)
+#endif
static char *copy;
@@ -70,7 +73,7 @@ do_test (void)
char *argv[] = { basename (copy), NULL };
errno = 0;
- execvp (argv[0], argv);
+ EXECVP (argv[0], argv);
if (errno != EACCES)
{
diff --git a/posix/tst-execvp3.c b/posix/tst-execvp3.c
index 5ebc879..43f7c34 100644
--- a/posix/tst-execvp3.c
+++ b/posix/tst-execvp3.c
@@ -12,6 +12,9 @@ static int do_test (void);
#include "../test-skeleton.c"
+#ifndef EXECVP
+# define EXECVP(__file, __argv) execvp (__file, __argv)
+#endif
static char *fname;
@@ -35,7 +38,7 @@ do_test (void)
}
char *argv[] = { fname, NULL };
- execvp (basename (fname), argv);
+ EXECVP (basename (fname), argv);
/* If we come here, the execvp call failed. */
return 1;
diff --git a/posix/tst-execvp4.c b/posix/tst-execvp4.c
index 531fab2..116624f 100644
--- a/posix/tst-execvp4.c
+++ b/posix/tst-execvp4.c
@@ -5,6 +5,10 @@
#include <unistd.h>
#include <sys/stat.h>
+#ifndef EXECVP
+# define EXECVP(__file, __argv) execvp (__file, __argv)
+#endif
+
static int
do_test (void)
{
@@ -27,7 +31,7 @@ do_test (void)
unsetenv ("PATH");
char *argv[] = { buf + 9, NULL };
- execvp (argv[0], argv);
+ EXECVP (argv[0], argv);
return 0;
}
diff --git a/posix/tst-execvpe1.c b/posix/tst-execvpe1.c
new file mode 100644
index 0000000..622eb79
--- /dev/null
+++ b/posix/tst-execvpe1.c
@@ -0,0 +1,20 @@
+/* Check ENOENT failure for execvpe.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#define EXECVP(file, argv) execvpe (file, argv, NULL)
+#include <posix/tst-execvp1.c>
diff --git a/posix/tst-execvpe2.c b/posix/tst-execvpe2.c
new file mode 100644
index 0000000..cdec09a
--- /dev/null
+++ b/posix/tst-execvpe2.c
@@ -0,0 +1,20 @@
+/* Check EACCES for execvpe.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#define EXECVP(file, argv) execvpe (file, argv, NULL)
+#include <posix/tst-execvp2.c>
diff --git a/posix/tst-execvpe3.c b/posix/tst-execvpe3.c
new file mode 100644
index 0000000..47cdc14
--- /dev/null
+++ b/posix/tst-execvpe3.c
@@ -0,0 +1,20 @@
+/* Check script execution without shebang for execvpe.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#define EXECVP(file, argv) execvpe (file, argv, NULL)
+#include <posix/tst-execvp3.c>
diff --git a/posix/tst-execvpe4.c b/posix/tst-execvpe4.c
new file mode 100644
index 0000000..e8883aa
--- /dev/null
+++ b/posix/tst-execvpe4.c
@@ -0,0 +1,20 @@
+/* Check unexistent binary for execvpe.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#define EXECVP(file, argv) execvpe (file, argv, NULL)
+#include <posix/tst-execvp4.c>
diff --git a/posix/tst-execvpe5.c b/posix/tst-execvpe5.c
new file mode 100644
index 0000000..81085ba
--- /dev/null
+++ b/posix/tst-execvpe5.c
@@ -0,0 +1,157 @@
+/* General tests for execpve.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wait.h>
+
+
+/* Nonzero if the program gets called via `exec'. */
+static int restart;
+
+
+#define CMDLINE_OPTIONS \
+ { "restart", no_argument, &restart, 1 },
+
+/* Prototype for our test function. */
+extern void do_prepare (int argc, char *argv[]);
+extern int do_test (int argc, char *argv[]);
+
+#include "../test-skeleton.c"
+
+#define EXECVPE_KEY "EXECVPE_ENV"
+#define EXECVPE_VALUE "execvpe_test"
+
+
+static int
+handle_restart (void)
+{
+ /* First check if only one variable is passed on execvpe. */
+ int env_count = 0;
+ for (char **e = environ; *e != NULL; ++e)
+ if (++env_count == INT_MAX)
+ {
+ printf ("Environment variable number overflow");
+ exit (EXIT_FAILURE);
+ }
+ if (env_count != 1)
+ {
+ printf ("Wrong number of environment variables");
+ exit (EXIT_FAILURE);
+ }
+
+ /* Check if the combinarion os "EXECVPE_ENV=execvpe_test" */
+ const char *env = getenv (EXECVPE_KEY);
+ if (env == NULL)
+ {
+ printf ("Test environment variable not found");
+ exit (EXIT_FAILURE);
+ }
+
+ if (strncmp (env, EXECVPE_VALUE, sizeof (EXECVPE_VALUE)))
+ {
+ printf ("Test environment variable with wrong value");
+ exit (EXIT_FAILURE);
+ }
+
+ return 0;
+}
+
+
+int
+do_test (int argc, char *argv[])
+{
+ pid_t pid;
+ int status;
+
+ /* We must have
+ - one or four parameters left if called initially
+ + path for ld.so optional
+ + "--library-path" optional
+ + the library path optional
+ + the application name
+ */
+
+ if (restart)
+ {
+ if (argc != 1)
+ {
+ printf ("Wrong number of arguments (%d)", argc);
+ exit (EXIT_FAILURE);
+ }
+
+ return handle_restart ();
+ }
+
+ if (argc != 2 && argc != 5)
+ {
+ printf ("Wrong number of arguments (%d)", argc);
+ exit (EXIT_FAILURE);
+ }
+
+ /* We want to test the `execvpe' function. To do this we restart the
+ program with an additional parameter. */
+ pid = fork ();
+ if (pid == 0)
+ {
+ /* This is the child. Construct the command line. */
+
+ /* We cast here to char* because the test itself does not modify neither
+ the argument nor the environment list. */
+ char *envs[] = { (char*)(EXECVPE_KEY "=" EXECVPE_VALUE), NULL };
+ if (argc == 5)
+ {
+ char *args[] = { argv[1], argv[2], argv[3], argv[4],
+ (char *) "--direct", (char *) "--restart", NULL };
+ execvpe (args[0], args, envs);
+ }
+ else
+ {
+ char *args[] = { argv[1], argv[1],
+ (char *) "--direct", (char *) "--restart", NULL };
+ execvpe (args[0], args, envs);
+ }
+
+ printf ("Cannot exec");
+ exit (EXIT_FAILURE);
+ }
+ else if (pid == (pid_t) -1)
+ {
+ printf ("Cannot fork");
+ exit (EXIT_FAILURE);
+ }
+
+ /* Wait for the child. */
+ if (waitpid (pid, &status, 0) != pid)
+ {
+ printf ("Wrong child");
+ exit (EXIT_FAILURE);
+ }
+
+ if (WTERMSIG (status) != 0)
+ {
+ printf ("Child terminated incorrectly");
+ exit (EXIT_FAILURE);
+ }
+ status = WEXITSTATUS (status);
+
+ return status;
+}
diff --git a/posix/tst-execvpe6.c b/posix/tst-execvpe6.c
new file mode 100644
index 0000000..4551e2c
--- /dev/null
+++ b/posix/tst-execvpe6.c
@@ -0,0 +1,82 @@
+/* Check execvpe script argument handling.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/param.h>
+
+static char *fname;
+
+static void do_prepare (void);
+#define PREPARE(argc, argv) do_prepare ()
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+
+#include "../test-skeleton.c"
+
+static void
+do_prepare (void)
+{
+ int fd = create_temp_file ("testscript", &fname);
+ dprintf (fd, "echo foo\n");
+ fchmod (fd, 0700);
+ close (fd);
+}
+
+static int
+do_test (void)
+{
+ if (setenv ("PATH", test_dir, 1) != 0)
+ {
+ puts ("setenv failed");
+ return 1;
+ }
+
+ /* To limit stack allocation for argument construction in case of
+ script without shebang execvpe limits total number of argument
+ to NCARGS. */
+ const size_t max_args = NCARGS + 1;
+ char **args = malloc ((NCARGS + 1) * sizeof (char*));
+ if (args == NULL)
+ {
+ puts ("malloc failed");
+ return 1;
+ }
+
+ args[0] = fname;
+ for (int i = 1; i < max_args; ++i)
+ args[i] = strdup ("a");
+ args[max_args] = NULL;
+
+ execvpe (basename (fname), args, NULL);
+
+ for (int i = 1; i < max_args; ++i)
+ free (args[i]);
+ free (args);
+
+ if (errno != E2BIG)
+ {
+ printf ("errno = %d (%m), expected E2BIG\n", errno);
+ return 1;
+ }
+
+ return 0;
+}
--
1.9.1
^ permalink raw reply [flat|nested] 28+ messages in thread
* [PATCH 0/3] posix: Execute file function fixes
@ 2016-02-26 13:57 Adhemerval Zanella
2016-02-26 13:57 ` [PATCH 3/3] posix: New Linux posix_spawn{p} implementation Adhemerval Zanella
` (2 more replies)
0 siblings, 3 replies; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 13:57 UTC (permalink / raw)
To: libc-alpha
This is an update from my previous patchset with fixes based on previous
comments. The differences from previous version are:
* Add a limit check for total number of arguments to avoid signed overflow
handling. Current limit of argument for execl{e,p}, execvpe and
posix_spawn{p} is INT_MAX.
* Add some comments clarifing the problems with dynamic memory allocations
for exec family functions.
--
This patchset add some cleanup and fixes for the exec{l,le,lp,vpe}
general function implementation and fixes long standing bugs for
posix_spawn{p} on Linux. It is basically my previous 2 patchset
for execvpe and posix_spawn{p} along with the execl{e,p} fixes.
For exe{l,le,lp,vpe} function main difference is using stack allocation
instead of dynamic one for argument handling. The main difference from
previous patch iteration is it does not add any memory stack allocation
constraints due:
1. Current GLIBC logic to limit stack allocation through __MAX_ALLOCA_CUTOFF
is arbitrary and does no impose any limit (it does not consider current
stack size neither stack size limit).
2. Memory allocation constraints associated with the functions make
stack allocation the only sane option. All exec function family are
defined to be async-safe, where they can be called either through a
signal handler or in vfork child, and they can not really on dynamic
memory allocation (either through malloc or directly by mmap).
The posix_spawn{p} is a new implementation for Linux which aims to
fix some long-standing bug regarding signal handling. It also
tries to avoid dynamic memory allocation by either relying on the
exec{l,vpe} functions with a dynamic mmap memory region allocate
to use along with direct created child (using clone syscall).
Adhemerval Zanella (3):
posix: Remove dynamic memory allocation from execl{e,p}
posix: execvpe cleanup
posix: New Linux posix_spawn{p} implementation
ChangeLog | 54 +++
include/sched.h | 2 +
include/unistd.h | 1 +
posix/Makefile | 7 +-
posix/execl.c | 69 ++--
posix/execle.c | 70 ++--
posix/execlp.c | 67 ++--
posix/execvpe.c | 244 +++++-------
posix/tst-execvp1.c | 6 +-
posix/tst-execvp2.c | 5 +-
posix/tst-execvp3.c | 5 +-
posix/tst-execvp4.c | 6 +-
posix/tst-execvpe1.c | 20 +
posix/tst-execvpe2.c | 20 +
posix/tst-execvpe3.c | 20 +
posix/tst-execvpe4.c | 20 +
posix/tst-execvpe5.c | 157 ++++++++
posix/tst-execvpe6.c | 82 ++++
posix/tst-spawn2.c | 73 ++++
sysdeps/posix/dup.c | 2 +-
sysdeps/unix/sysv/linux/aarch64/clone.S | 1 +
sysdeps/unix/sysv/linux/alpha/clone.S | 1 +
sysdeps/unix/sysv/linux/arm/clone.S | 1 +
sysdeps/unix/sysv/linux/hppa/clone.S | 1 +
sysdeps/unix/sysv/linux/i386/clone.S | 1 +
sysdeps/unix/sysv/linux/ia64/clone2.S | 2 +
sysdeps/unix/sysv/linux/m68k/clone.S | 1 +
sysdeps/unix/sysv/linux/microblaze/clone.S | 1 +
sysdeps/unix/sysv/linux/mips/clone.S | 1 +
sysdeps/unix/sysv/linux/nios2/clone.S | 1 +
sysdeps/unix/sysv/linux/nptl-signals.h | 10 +
sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S | 1 +
sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S | 1 +
sysdeps/unix/sysv/linux/s390/s390-32/clone.S | 2 +
sysdeps/unix/sysv/linux/s390/s390-64/clone.S | 2 +
sysdeps/unix/sysv/linux/sh/clone.S | 1 +
sysdeps/unix/sysv/linux/sparc/sparc32/clone.S | 1 +
sysdeps/unix/sysv/linux/sparc/sparc64/clone.S | 1 +
sysdeps/unix/sysv/linux/spawni.c | 445 ++++++++++++++++++++++
sysdeps/unix/sysv/linux/tile/clone.S | 1 +
sysdeps/unix/sysv/linux/x86_64/clone.S | 1 +
41 files changed, 1133 insertions(+), 274 deletions(-)
create mode 100644 posix/tst-execvpe1.c
create mode 100644 posix/tst-execvpe2.c
create mode 100644 posix/tst-execvpe3.c
create mode 100644 posix/tst-execvpe4.c
create mode 100644 posix/tst-execvpe5.c
create mode 100644 posix/tst-execvpe6.c
create mode 100644 posix/tst-spawn2.c
create mode 100644 sysdeps/unix/sysv/linux/spawni.c
--
1.9.1
^ permalink raw reply [flat|nested] 28+ messages in thread
* [PATCH 3/3] posix: New Linux posix_spawn{p} implementation
2016-02-26 13:57 [PATCH 0/3] posix: Execute file function fixes Adhemerval Zanella
@ 2016-02-26 13:57 ` Adhemerval Zanella
2016-02-26 17:33 ` Joseph Myers
2016-02-26 20:49 ` Paul Eggert
2016-02-26 13:57 ` [PATCH 2/3] posix: execvpe cleanup Adhemerval Zanella
2016-02-26 14:19 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
2 siblings, 2 replies; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 13:57 UTC (permalink / raw)
To: libc-alpha
This patch implements a new posix_spawn{p} implementation for Linux. The main
difference is it uses the clone syscall directly with CLONE_VM and CLONE_VFORK
flags and a direct allocated stack. The new stack and start function solves
most the vfork limitation (possible parent clobber due stack spilling). The
remaning issue are related to signal handling:
1. That no signal handlers must run in child context, to avoid corrupt
parent's state.
2. Child must synchronize with parent to enforce stack deallocation and
to possible return execv issues.
The first one is solved by blocking all signals in child, even NPTL-internal
ones (SIGCANCEL and SIGSETXID). The second issue is done by a stack allocation
in parent and a synchronization with using a pipe or waitpid (in case or error).
The pipe has the advantage of allowing the child signal an exec error (checked
with new tst-spawn2 test).
There is an inherent race condition in pipe2 usage for architectures that do not
support the syscall directly. In such cases the a pipe plus fctnl is used
instead and it may lead to file descriptor leak in parent (as decribed by fcntl
documentation).
The child process stack is allocate with a mmap with MAP_STACK flag using
default architecture stack size. Although it is slower than use a stack buffer
from parent, it allows some slack for the compatibility code to run scripts
with no shebang (which may use a buffer with size depending of argument list
count).
Performance should be similar to the vfork default posix implementation and
way faster than fork path (vfork on mostly linux ports are basically
clone with CLONE_VM plus CLONE_VFORK). The only difference is the syscalls
required for the stack allocation/deallocation.
It fixes BZ#10354, BZ#14750, and BZ#18433.
Tested on i386, x86_64, powerpc64le, and aarch64.
[BZ #14750]
[BZ #10354]
[BZ #18433]
* include/sched.h (__clone): Add hidden prototype.
(__clone2): Likewise.
* include/unistd.h (__dup): Likewise.
* posix/Makefile (tests): Add tst-spawn2.
* posix/tst-spawn2.c: New file.
* sysdeps/posix/dup.c (__dup): Add hidden definition.
* sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/alpha/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/hppa/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/i386/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/ia64/clone2.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/m68k/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/microblaze/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/mips/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/nios2/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S (__clone):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone):
Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/sh/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/tile/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/x86_64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/nptl-signals.h
(____nptl_is_internal_signal): New function.
* sysdeps/unix/sysv/linux/spawni.c: New file.
---
include/sched.h | 2 +
include/unistd.h | 1 +
posix/Makefile | 2 +-
posix/tst-spawn2.c | 73 ++++
sysdeps/posix/dup.c | 2 +-
sysdeps/unix/sysv/linux/aarch64/clone.S | 1 +
sysdeps/unix/sysv/linux/alpha/clone.S | 1 +
sysdeps/unix/sysv/linux/arm/clone.S | 1 +
sysdeps/unix/sysv/linux/hppa/clone.S | 1 +
sysdeps/unix/sysv/linux/i386/clone.S | 1 +
sysdeps/unix/sysv/linux/ia64/clone2.S | 2 +
sysdeps/unix/sysv/linux/m68k/clone.S | 1 +
sysdeps/unix/sysv/linux/microblaze/clone.S | 1 +
sysdeps/unix/sysv/linux/mips/clone.S | 1 +
sysdeps/unix/sysv/linux/nios2/clone.S | 1 +
sysdeps/unix/sysv/linux/nptl-signals.h | 10 +
sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S | 1 +
sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S | 1 +
sysdeps/unix/sysv/linux/s390/s390-32/clone.S | 2 +
sysdeps/unix/sysv/linux/s390/s390-64/clone.S | 2 +
sysdeps/unix/sysv/linux/sh/clone.S | 1 +
sysdeps/unix/sysv/linux/sparc/sparc32/clone.S | 1 +
sysdeps/unix/sysv/linux/sparc/sparc64/clone.S | 1 +
sysdeps/unix/sysv/linux/spawni.c | 445 ++++++++++++++++++++++
sysdeps/unix/sysv/linux/tile/clone.S | 1 +
sysdeps/unix/sysv/linux/x86_64/clone.S | 1 +
27 files changed, 589 insertions(+), 2 deletions(-)
create mode 100644 posix/tst-spawn2.c
create mode 100644 sysdeps/unix/sysv/linux/spawni.c
diff --git a/include/sched.h b/include/sched.h
index 4f59397..b4d7406 100644
--- a/include/sched.h
+++ b/include/sched.h
@@ -19,7 +19,9 @@ extern int __sched_rr_get_interval (__pid_t __pid, struct timespec *__t);
/* These are Linux specific. */
extern int __clone (int (*__fn) (void *__arg), void *__child_stack,
int __flags, void *__arg, ...);
+libc_hidden_proto (__clone)
extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
size_t __child_stack_size, int __flags, void *__arg, ...);
+libc_hidden_proto (__clone2)
#endif
#endif
diff --git a/include/unistd.h b/include/unistd.h
index 5152f64..d2802b2 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -81,6 +81,7 @@ char *__canonicalize_directory_name_internal (const char *__thisdir,
size_t __size) attribute_hidden;
extern int __dup (int __fd);
+libc_hidden_proto (__dup)
extern int __dup2 (int __fd, int __fd2);
libc_hidden_proto (__dup2)
extern int __dup3 (int __fd, int __fd2, int flags);
diff --git a/posix/Makefile b/posix/Makefile
index a2aabcc..a38a3a6 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -94,7 +94,7 @@ tests := tstgetopt testfnm runtests runptests \
xtests := bug-ga2
ifeq (yes,$(build-shared))
test-srcs := globtest
-tests += wordexp-test tst-exec tst-spawn
+tests += wordexp-test tst-exec tst-spawn tst-spawn2
endif
tests-static = tst-exec-static tst-spawn-static
tests += $(tests-static)
diff --git a/posix/tst-spawn2.c b/posix/tst-spawn2.c
new file mode 100644
index 0000000..41bfde8
--- /dev/null
+++ b/posix/tst-spawn2.c
@@ -0,0 +1,73 @@
+/* Further tests for spawn in case of invalid binary paths.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <spawn.h>
+#include <error.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#include <stdio.h>
+
+int
+posix_spawn_test (void)
+{
+ /* Check if posix_spawn correctly returns an error and an invalid pid
+ by trying to spawn an invalid binary. */
+
+ const char *program = "/path/to/invalid/binary";
+ char * const args[] = { 0 };
+ pid_t pid = -1;
+
+ int ret = posix_spawn (&pid, program, 0, 0, args, environ);
+ if (ret != ENOENT)
+ error (EXIT_FAILURE, errno, "posix_spawn");
+
+ /* POSIX states the value returned on pid variable in case of an error
+ is not specified. GLIBC will update the value iff the child
+ execution is successful. */
+ if (pid != -1)
+ error (EXIT_FAILURE, errno, "posix_spawn returned pid != -1");
+
+ /* Check if no child is actually created. */
+ ret = waitpid (-1, NULL, 0);
+ if (ret != -1 || errno != ECHILD)
+ error (EXIT_FAILURE, errno, "waitpid");
+
+ /* Same as before, but with posix_spawnp. */
+ char *args2[] = { (char*) program, 0 };
+
+ ret = posix_spawnp (&pid, args2[0], 0, 0, args2, environ);
+ if (ret != ENOENT)
+ error (EXIT_FAILURE, errno, "posix_spawnp");
+
+ if (pid != -1)
+ error (EXIT_FAILURE, errno, "posix_spawnp returned pid != -1");
+
+ ret = waitpid (-1, NULL, 0);
+ if (ret != -1 || errno != ECHILD)
+ error (EXIT_FAILURE, errno, "waitpid");
+
+ return 0;
+}
+
+#define TEST_FUNCTION posix_spawn_test ()
+#include "../test-skeleton.c"
+
diff --git a/sysdeps/posix/dup.c b/sysdeps/posix/dup.c
index 9525e76..abf3ff5 100644
--- a/sysdeps/posix/dup.c
+++ b/sysdeps/posix/dup.c
@@ -26,5 +26,5 @@ __dup (int fd)
{
return fcntl (fd, F_DUPFD, 0);
}
-
+libc_hidden_def (__dup)
weak_alias (__dup, dup)
diff --git a/sysdeps/unix/sysv/linux/aarch64/clone.S b/sysdeps/unix/sysv/linux/aarch64/clone.S
index 596fb9c..8f3ab40 100644
--- a/sysdeps/unix/sysv/linux/aarch64/clone.S
+++ b/sysdeps/unix/sysv/linux/aarch64/clone.S
@@ -93,4 +93,5 @@ thread_start:
cfi_endproc
.size thread_start, .-thread_start
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/alpha/clone.S b/sysdeps/unix/sysv/linux/alpha/clone.S
index ec9c06d..556aa63 100644
--- a/sysdeps/unix/sysv/linux/alpha/clone.S
+++ b/sysdeps/unix/sysv/linux/alpha/clone.S
@@ -137,4 +137,5 @@ thread_start:
cfi_endproc
.end thread_start
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/arm/clone.S b/sysdeps/unix/sysv/linux/arm/clone.S
index 460a8f5..c103123 100644
--- a/sysdeps/unix/sysv/linux/arm/clone.S
+++ b/sysdeps/unix/sysv/linux/arm/clone.S
@@ -93,4 +93,5 @@ PSEUDO_END (__clone)
.fnend
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/hppa/clone.S b/sysdeps/unix/sysv/linux/hppa/clone.S
index e80fd8d..0a18137 100644
--- a/sysdeps/unix/sysv/linux/hppa/clone.S
+++ b/sysdeps/unix/sysv/linux/hppa/clone.S
@@ -175,4 +175,5 @@ ENTRY(__clone)
PSEUDO_END(__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/i386/clone.S b/sysdeps/unix/sysv/linux/i386/clone.S
index 7d818c1..ef447d1 100644
--- a/sysdeps/unix/sysv/linux/i386/clone.S
+++ b/sysdeps/unix/sysv/linux/i386/clone.S
@@ -139,4 +139,5 @@ L(nomoregetpid):
cfi_startproc
PSEUDO_END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/ia64/clone2.S b/sysdeps/unix/sysv/linux/ia64/clone2.S
index 9b257b3..fc046eb 100644
--- a/sysdeps/unix/sysv/linux/ia64/clone2.S
+++ b/sysdeps/unix/sysv/linux/ia64/clone2.S
@@ -96,6 +96,8 @@ ENTRY(__clone2)
ret /* Not reached. */
PSEUDO_END(__clone2)
+libc_hidden_def (__clone2)
+
/* For now we leave __clone undefined. This is unlikely to be a */
/* problem, since at least the i386 __clone in glibc always failed */
/* with a 0 sp (eventhough the kernel explicitly handled it). */
diff --git a/sysdeps/unix/sysv/linux/m68k/clone.S b/sysdeps/unix/sysv/linux/m68k/clone.S
index 8b40df2..33474cc 100644
--- a/sysdeps/unix/sysv/linux/m68k/clone.S
+++ b/sysdeps/unix/sysv/linux/m68k/clone.S
@@ -127,4 +127,5 @@ donepid:
cfi_startproc
PSEUDO_END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/microblaze/clone.S b/sysdeps/unix/sysv/linux/microblaze/clone.S
index 035d88b..cbc95ce 100644
--- a/sysdeps/unix/sysv/linux/microblaze/clone.S
+++ b/sysdeps/unix/sysv/linux/microblaze/clone.S
@@ -69,4 +69,5 @@ L(thread_start):
nop
PSEUDO_END(__clone)
+libc_hidden_def (__clone)
weak_alias (__clone,clone)
diff --git a/sysdeps/unix/sysv/linux/mips/clone.S b/sysdeps/unix/sysv/linux/mips/clone.S
index 755e8cc..feb8250 100644
--- a/sysdeps/unix/sysv/linux/mips/clone.S
+++ b/sysdeps/unix/sysv/linux/mips/clone.S
@@ -166,4 +166,5 @@ L(gotpid):
END(__thread_start)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/nios2/clone.S b/sysdeps/unix/sysv/linux/nios2/clone.S
index 4da5c19..e4d3970 100644
--- a/sysdeps/unix/sysv/linux/nios2/clone.S
+++ b/sysdeps/unix/sysv/linux/nios2/clone.S
@@ -104,4 +104,5 @@ thread_start:
cfi_startproc
PSEUDO_END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/nptl-signals.h b/sysdeps/unix/sysv/linux/nptl-signals.h
index 7560a21..01f34c2 100644
--- a/sysdeps/unix/sysv/linux/nptl-signals.h
+++ b/sysdeps/unix/sysv/linux/nptl-signals.h
@@ -16,6 +16,8 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <signal.h>
+
/* The signal used for asynchronous cancelation. */
#define SIGCANCEL __SIGRTMIN
@@ -29,5 +31,13 @@
/* Signal used to implement the setuid et.al. functions. */
#define SIGSETXID (__SIGRTMIN + 1)
+
+/* Return is sig is used internally. */
+static inline int
+__nptl_is_internal_signal (int sig)
+{
+ return (sig == SIGCANCEL) || (sig == SIGTIMER) || (sig == SIGSETXID);
+}
+
/* Used to communicate with signal handler. */
extern struct xid_command *__xidcmd attribute_hidden;
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
index 28948ea..eb973db 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
@@ -108,4 +108,5 @@ L(badargs):
cfi_startproc
END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
index c8c6de8..959fdb7 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
@@ -126,4 +126,5 @@ L(parent):
END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/clone.S b/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
index cb2afbb..f774e90 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
@@ -70,4 +70,6 @@ thread_start:
xc 0(4,%r15),0(%r15)
basr %r14,%r1 /* jump to fn */
DO_CALL (exit, 1)
+
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/clone.S b/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
index eddab35..928a881 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
@@ -73,4 +73,6 @@ thread_start:
xc 0(8,%r15),0(%r15)
basr %r14,%r1 /* jump to fn */
DO_CALL (exit, 1)
+
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/sh/clone.S b/sysdeps/unix/sysv/linux/sh/clone.S
index 53cc08b..a73dd7d 100644
--- a/sysdeps/unix/sysv/linux/sh/clone.S
+++ b/sysdeps/unix/sysv/linux/sh/clone.S
@@ -123,4 +123,5 @@ ENTRY(__clone)
.word TID - TLS_PRE_TCB_SIZE
PSEUDO_END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S b/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
index 6f41f0f..68f8202 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
@@ -100,4 +100,5 @@ __thread_start:
.size __thread_start, .-__thread_start
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S b/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
index e2d3914..cecffa7 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
@@ -96,4 +96,5 @@ __thread_start:
.size __thread_start, .-__thread_start
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
new file mode 100644
index 0000000..ca1d34d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/spawni.c
@@ -0,0 +1,445 @@
+/* POSIX spawn interface. Linux version.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <spawn.h>
+#include <fcntl.h>
+#include <paths.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <sys/wait.h>
+#include <sys/param.h>
+#include <sys/mman.h>
+#include <not-cancel.h>
+#include <local-setxid.h>
+#include <shlib-compat.h>
+#include <nptl/pthreadP.h>
+#include <dl-sysdep.h>
+#include <ldsodefs.h>
+#include "spawn_int.h"
+
+/* The Linux implementation of posix_spawn{p} uses the clone syscall directly
+ with CLONE_VM and CLONE_VFORK flags and an allocated stack. The new stack
+ and start function solves most the vfork limitation (possible parent
+ clobber due stack spilling). The remaning issue are:
+
+ 1. That no signal handlers must run in child context, to avoid corrupt
+ parent's state.
+ 2. The parent must ensure child's stack freeing.
+ 3. Child must synchronize with parent to enforce 2. and to possible
+ return execv issues.
+
+ The first issue is solved by blocking all signals in child, even the
+ NPTL-internal ones (SIGCANCEL and SIGSETXID). The second and third issue
+ is done by a stack allocation in parent and a synchronization with using
+ a pipe or waitpid (in case or error). The pipe has the advantage of
+ allowing the child the signal an exec error. */
+
+
+/* The Unix standard contains a long explanation of the way to signal
+ an error after the fork() was successful. Since no new wait status
+ was wanted there is no way to signal an error using one of the
+ available methods. The committee chose to signal an error by a
+ normal program exit with the exit code 127. */
+#define SPAWN_ERROR 127
+
+/* We need to block both SIGCANCEL and SIGSETXID. */
+#define SIGALL_SET \
+ ((__sigset_t) { .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 } })
+
+#ifdef __ia64__
+# define CLONE(__fn, __stack, __stacksize, __flags, __args) \
+ __clone2 (__fn, __stack, __stacksize, __flags, __args, 0, 0, 0)
+#else
+# define CLONE(__fn, __stack, __stacksize, __flags, __args) \
+ __clone (__fn, __stack, __flags, __args)
+#endif
+
+#if _STACK_GROWS_DOWN
+# define STACK(__stack, __stack_size) (__stack + __stack_size)
+#elif _STACK_GROWS_UP
+# define STACK(__stack, __stack_size) (__stack)
+#endif
+
+/* Issues a 'pipe2' when the architecture supports or a 'pipe' plus O_CLOEXEC
+ otherwise. When pipe2 syscall is not available the pipe plus fcntl have a
+ inherent race condition (pipe2 is the right solution to avoid it). */
+
+#ifdef __ASSUME_PIPE2
+# define __have_pipe2 1
+#endif
+
+static int
+__do_pipe2_cloexec (int pipe_fds[2])
+{
+ /* Try pipe2 even if __ASSUME_PIPE2 is not define and returning an error
+ iff the call returns ENOSYS. */
+ int r = -1;
+ if (__have_pipe2 >= 0)
+ {
+ r = __pipe2 (pipe_fds, O_CLOEXEC);
+#ifndef __ASSUME_PIPE2
+ if (__have_pipe2 == 0)
+ __have_pipe2 = r != -1 || errno != ENOSYS ? 1 : -1;
+#endif
+
+ if (__have_pipe2 > 0)
+ return r;
+ }
+ if (__have_pipe2 < 0)
+ if (__pipe (pipe_fds) < 0)
+ return -1;
+
+ /* Then apply FD_CLOCEXEC if it is supported in the pipe call case. */
+ if (__have_pipe2 < 0)
+ {
+ if ((r = __fcntl (pipe_fds[0], F_SETFD, FD_CLOEXEC)) == -1
+ || (r = __fcntl (pipe_fds[1], F_SETFD, FD_CLOEXEC)) == -1)
+ {
+ close_not_cancel (pipe_fds[0]);
+ close_not_cancel (pipe_fds[1]);
+ return r;
+ }
+ }
+
+ return r;
+}
+
+struct posix_spawn_args
+{
+ int pipe[2];
+ sigset_t oldmask;
+ const char *file;
+ int (*exec) (const char *, char *const *, char *const *);
+ const posix_spawn_file_actions_t *fa;
+ const posix_spawnattr_t *restrict attr;
+ char *const *argv;
+ int argc;
+ char *const *envp;
+ int xflags;
+};
+
+/* Older version requires that shell script without shebang definition
+ to be called explicity using /bin/sh (_PATH_BSHELL). */
+static void
+maybe_script_execute (struct posix_spawn_args *args)
+{
+ if (SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_15)
+ && (args->xflags & SPAWN_XFLAGS_TRY_SHELL) && errno == ENOEXEC)
+ {
+ char *const *argv = args->argv;
+ int argc = args->argc;
+
+ /* Construct an argument list for the shell. */
+ char *new_argv[argc];
+ new_argv[0] = (char *) _PATH_BSHELL;
+ new_argv[1] = (char *) args->file;
+ while (argc > 1)
+ {
+ new_argv[argc] = argv[argc - 1];
+ --argc;
+ }
+
+ /* Execute the shell. */
+ args->exec (new_argv[0], new_argv, args->envp);
+ }
+}
+
+/* Function used in the clone call to setup the signals mask, posix_spawn
+ attributes, and file actions. It run on its own stack (provided by the
+ posix_spawn call). */
+static int
+__spawni_child (void *arguments)
+{
+ struct posix_spawn_args *args = arguments;
+ const posix_spawnattr_t *restrict attr = args->attr;
+ const posix_spawn_file_actions_t *file_actions = args->fa;
+ int p = args->pipe[1];
+ int ret;
+
+ close_not_cancel (args->pipe[0]);
+
+ /* The child must ensure that no signal handler are enabled because it shared
+ memory with parent, so the signal disposition must be either SIG_DFL or
+ SIG_IGN. It does by iterating over all signals and although it could
+ possibly be more optimized (by tracking which signal potentially have a
+ signal handler), it might requires system specific solutions (since the
+ sigset_t data type can be very different on different architectures). */
+ struct sigaction sa;
+ memset (&sa, '\0', sizeof (sa));
+
+ sigset_t hset;
+ __sigprocmask (SIG_BLOCK, 0, &hset);
+ for (int sig = 1; sig < _NSIG; ++sig)
+ {
+ if ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
+ && sigismember (&attr->__sd, sig))
+ {
+ sa.sa_handler = SIG_DFL;
+ }
+ else if (sigismember (&hset, sig))
+ {
+ if (__nptl_is_internal_signal (sig))
+ sa.sa_handler = SIG_IGN;
+ else
+ {
+ __libc_sigaction (sig, 0, &sa);
+ if (sa.sa_handler == SIG_IGN)
+ continue;
+ sa.sa_handler = SIG_DFL;
+ }
+ }
+ else
+ continue;
+
+ __libc_sigaction (sig, &sa, 0);
+ }
+
+#ifdef _POSIX_PRIORITY_SCHEDULING
+ /* Set the scheduling algorithm and parameters. */
+ if ((attr->__flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER))
+ == POSIX_SPAWN_SETSCHEDPARAM)
+ {
+ if ((ret = __sched_setparam (0, &attr->__sp)) == -1)
+ goto fail;
+ }
+ else if ((attr->__flags & POSIX_SPAWN_SETSCHEDULER) != 0)
+ {
+ if ((ret = __sched_setscheduler (0, attr->__policy, &attr->__sp)) == -1)
+ goto fail;
+ }
+#endif
+
+ /* Set the process group ID. */
+ if ((attr->__flags & POSIX_SPAWN_SETPGROUP) != 0
+ && (ret = __setpgid (0, attr->__pgrp)) != 0)
+ goto fail;
+
+ /* Set the effective user and group IDs. */
+ if ((attr->__flags & POSIX_SPAWN_RESETIDS) != 0
+ && ((ret = local_seteuid (__getuid ())) != 0
+ || (ret = local_setegid (__getgid ())) != 0))
+ goto fail;
+
+ /* Execute the file actions. */
+ if (file_actions != 0)
+ {
+ int cnt;
+ struct rlimit64 fdlimit;
+ bool have_fdlimit = false;
+
+ for (cnt = 0; cnt < file_actions->__used; ++cnt)
+ {
+ struct __spawn_action *action = &file_actions->__actions[cnt];
+
+ /* Dup the pipe fd onto an unoccupied one to avoid any file
+ operation to clobber it. */
+ if ((action->action.close_action.fd == p)
+ || (action->action.open_action.fd == p)
+ || (action->action.dup2_action.fd == p))
+ {
+ if ((ret = __dup (p)) < 0)
+ goto fail;
+ p = ret;
+ }
+
+ switch (action->tag)
+ {
+ case spawn_do_close:
+ if ((ret =
+ close_not_cancel (action->action.close_action.fd)) != 0)
+ {
+ if (!have_fdlimit)
+ {
+ __getrlimit64 (RLIMIT_NOFILE, &fdlimit);
+ have_fdlimit = true;
+ }
+
+ /* Signal errors only for file descriptors out of range. */
+ if (action->action.close_action.fd < 0
+ || action->action.close_action.fd >= fdlimit.rlim_cur)
+ goto fail;
+ }
+ break;
+
+ case spawn_do_open:
+ {
+ ret = open_not_cancel (action->action.open_action.path,
+ action->action.
+ open_action.oflag | O_LARGEFILE,
+ action->action.open_action.mode);
+
+ if (ret == -1)
+ goto fail;
+
+ int new_fd = ret;
+
+ /* Make sure the desired file descriptor is used. */
+ if (ret != action->action.open_action.fd)
+ {
+ if ((ret = __dup2 (new_fd, action->action.open_action.fd))
+ != action->action.open_action.fd)
+ goto fail;
+
+ if ((ret = close_not_cancel (new_fd)) != 0)
+ goto fail;
+ }
+ }
+ break;
+
+ case spawn_do_dup2:
+ if ((ret = __dup2 (action->action.dup2_action.fd,
+ action->action.dup2_action.newfd))
+ != action->action.dup2_action.newfd)
+ goto fail;
+ break;
+ }
+ }
+ }
+
+ /* Set the initial signal mask of the child if POSIX_SPAWN_SETSIGMASK
+ is set, otherwise restore the previous one. */
+ __sigprocmask (SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK)
+ ? &attr->__ss : &args->oldmask, 0);
+
+ args->exec (args->file, args->argv, args->envp);
+
+ /* This is compatibility function required to enable posix_spawn run
+ script without shebang definition for older posix_spawn versions
+ (2.15). */
+ maybe_script_execute (args);
+
+ ret = -errno;
+
+fail:
+ /* Since sizeof errno < PIPE_BUF, the write is atomic. */
+ ret = -ret;
+ if (ret)
+ while (write_not_cancel (p, &ret, sizeof ret) < 0)
+ continue;
+ exit (SPAWN_ERROR);
+}
+
+/* Spawn a new process executing PATH with the attributes describes in *ATTRP.
+ Before running the process perform the actions described in FILE-ACTIONS. */
+static int
+__spawnix (pid_t * pid, const char *file,
+ const posix_spawn_file_actions_t * file_actions,
+ const posix_spawnattr_t * attrp, char *const argv[],
+ char *const envp[], int xflags,
+ int (*exec) (const char *, char *const *, char *const *))
+{
+ pid_t new_pid;
+ struct posix_spawn_args args;
+ int ec;
+
+ if (__do_pipe2_cloexec (args.pipe))
+ return errno;
+
+ /* To avoid impose hard limits on posix_spawn{p} total number of arguments
+ it first calculates its number to allocate a mmap to hold all possible
+ valus. */
+ int argc = 0;
+ /* Linux allows at most max (0x7FFFFFFF, 1/4 stack size) arguments
+ to be used in a execve call. */
+ int limit = INT_MAX;
+ while (argv[argc++] != NULL)
+ if (limit <= argc)
+ {
+ errno = E2BIG;
+ return errno;
+ }
+
+ const int prot = (PROT_READ | PROT_WRITE
+ | ((GL (dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
+
+ /* Add a slack area to child own stack. */
+ const size_t argv_size = (argc * sizeof (void *)) + 512;
+ const size_t stack_size = ALIGN_UP (argv_size, GLRO(dl_pagesize));
+ void *stack = __mmap (NULL, stack_size, prot,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+ if (__glibc_unlikely (stack == MAP_FAILED))
+ {
+ close_not_cancel (args.pipe[0]);
+ close_not_cancel (args.pipe[1]);
+ return errno;
+ }
+
+ /* Disable asynchronous cancellation. */
+ int cs = LIBC_CANCEL_ASYNC ();
+
+ args.file = file;
+ args.exec = exec;
+ args.fa = file_actions;
+ args.attr = attrp ? attrp : &(const posix_spawnattr_t) { 0 };
+ args.argv = argv;
+ args.argc = argc;
+ args.envp = envp;
+ args.xflags = xflags;
+
+ __sigprocmask (SIG_BLOCK, &SIGALL_SET, &args.oldmask);
+
+ /* The clone flags used will create a new child that will run in the same
+ memory space (CLONE_VM) and the execution of calling thread will be
+ suspend until the child calls execve or _exit. These condition as
+ signal below either by pipe write (_exit with SPAWN_ERROR) or
+ a successful execve.
+ Also since the calling thread execution will be suspend, there is not
+ need for CLONE_SETTLS. Although parent and child share the same TLS
+ namespace, there will be no concurrent access for TLS variables (errno
+ for instance). */
+ new_pid = CLONE (__spawni_child, STACK (stack, stack_size), stack_size,
+ CLONE_VM | CLONE_VFORK | SIGCHLD, &args);
+
+ close_not_cancel (args.pipe[1]);
+
+ if (new_pid > 0)
+ {
+ if (__read (args.pipe[0], &ec, sizeof ec) != sizeof ec)
+ ec = 0;
+ else
+ __waitpid (new_pid, NULL, 0);
+ }
+ else
+ ec = -new_pid;
+
+ __munmap (stack, stack_size);
+
+ close_not_cancel (args.pipe[0]);
+
+ if (!ec && new_pid)
+ *pid = new_pid;
+
+ __sigprocmask (SIG_SETMASK, &args.oldmask, 0);
+
+ LIBC_CANCEL_RESET (cs);
+
+ return ec;
+}
+
+/* Spawn a new process executing PATH with the attributes describes in *ATTRP.
+ Before running the process perform the actions described in FILE-ACTIONS. */
+int
+__spawni (pid_t * pid, const char *file,
+ const posix_spawn_file_actions_t * acts,
+ const posix_spawnattr_t * attrp, char *const argv[],
+ char *const envp[], int xflags)
+{
+ if (xflags & SPAWN_XFLAGS_USE_PATH)
+ return __spawnix (pid, file, acts, attrp, argv, envp, xflags, __execvpe);
+ return __spawnix (pid, file, acts, attrp, argv, envp, xflags, __execve);
+}
diff --git a/sysdeps/unix/sysv/linux/tile/clone.S b/sysdeps/unix/sysv/linux/tile/clone.S
index 02fe3a8..a300eb5 100644
--- a/sysdeps/unix/sysv/linux/tile/clone.S
+++ b/sysdeps/unix/sysv/linux/tile/clone.S
@@ -219,4 +219,5 @@ ENTRY (__clone)
}
PSEUDO_END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
diff --git a/sysdeps/unix/sysv/linux/x86_64/clone.S b/sysdeps/unix/sysv/linux/x86_64/clone.S
index 382568a..1a50957 100644
--- a/sysdeps/unix/sysv/linux/x86_64/clone.S
+++ b/sysdeps/unix/sysv/linux/x86_64/clone.S
@@ -115,4 +115,5 @@ L(thread_start):
cfi_startproc;
PSEUDO_END (__clone)
+libc_hidden_def (__clone)
weak_alias (__clone, clone)
--
1.9.1
^ permalink raw reply [flat|nested] 28+ messages in thread
* [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-26 13:57 [PATCH 0/3] posix: Execute file function fixes Adhemerval Zanella
2016-02-26 13:57 ` [PATCH 3/3] posix: New Linux posix_spawn{p} implementation Adhemerval Zanella
2016-02-26 13:57 ` [PATCH 2/3] posix: execvpe cleanup Adhemerval Zanella
@ 2016-02-26 14:19 ` Adhemerval Zanella
2016-02-26 19:11 ` Paul Eggert
2 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 14:19 UTC (permalink / raw)
To: libc-alpha
GLIBC execl{e,p} implementation might use malloc if the total number of
arguments exceed initial assumption size (1024). This might lead to
issues in two situations:
1. execl/execle is stated to be async-signal-safe by POSIX [1]. However
if execl is used in a signal handler with a large argument set (that
may call malloc internally) and if the resulting call fails it might
lead malloc in the program in a bad state.
2. If the functions are used in a vfork/clone(VFORK) situation it also
might issue malloc internal bad state.
This patch fixes it by using stack allocation instead. It also fixes
BZ#19534.
Tested on x86_64.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html
[BZ #19534]
* posix/execl.c (execl): Remove dynamic memory allocation.
* posix/execle.c (execle): Likewise.
* posix/execlp.c (execlp): Likewise.
---
posix/Makefile | 2 +-
posix/execl.c | 69 ++++++++++++++++++++++-----------------------------------
posix/execle.c | 70 +++++++++++++++++++++++-----------------------------------
posix/execlp.c | 67 ++++++++++++++++++++++---------------------------------
5 files changed, 89 insertions(+), 126 deletions(-)
diff --git a/posix/Makefile b/posix/Makefile
index 4e90a95..55f4f31 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -221,8 +221,8 @@ CFLAGS-fexecve.os = -fomit-frame-pointer
CFLAGS-execv.os = -fomit-frame-pointer
CFLAGS-execle.os = -fomit-frame-pointer
CFLAGS-execl.os = -fomit-frame-pointer
-CFLAGS-execvp.os = -fomit-frame-pointer
CFLAGS-execlp.os = -fomit-frame-pointer
+CFLAGS-execvp.os = -fomit-frame-pointer
tstgetopt-ARGS = -a -b -cfoobar --required foobar --optional=bazbug \
--none random --col --color --colour
diff --git a/posix/execl.c b/posix/execl.c
index 102d19d..5584a4c 100644
--- a/posix/execl.c
+++ b/posix/execl.c
@@ -16,58 +16,43 @@
<http://www.gnu.org/licenses/>. */
#include <unistd.h>
+#include <errno.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
-
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until
a NULL pointer and environment from `environ'. */
int
execl (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
{
- if (i == argv_max)
+ if (argc == INT_MAX)
{
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
+ errno = E2BIG;
+ return -1;
}
-
- argv[i] = va_arg (args, const char *);
+ continue;
}
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, __environ);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ va_end (ap);
+
+ /* Avoid dynamic memory allocation due two main issues:
+ 1. The function should be async-signal-safe and a running on a signal
+ handler with a fail outcome might lead to malloc bad state.
+ 2. It might be used in a vfork/clone(VFORK) scenario where using
+ malloc also might lead to internal bad state. */
+ int i;
+ char *argv[argc + 1];
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i < argc; i++)
+ argv[i] = va_arg (ap, char *);
+ argv[i] = NULL;
+ va_end (ap);
+
+ return __execve (path, argv, __environ);
}
libc_hidden_def (execl)
diff --git a/posix/execle.c b/posix/execle.c
index 8edc03a..66b5738 100644
--- a/posix/execle.c
+++ b/posix/execle.c
@@ -17,57 +17,43 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until a NULL pointer,
and the argument after that for environment. */
int
execle (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
{
- if (i == argv_max)
+ if (argc == INT_MAX)
{
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
+ errno = E2BIG;
+ return -1;
}
-
- argv[i] = va_arg (args, const char *);
+ continue;
}
-
- const char *const *envp = va_arg (args, const char *const *);
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, (char *const *) envp);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ va_end (ap);
+
+ /* Avoid dynamic memory allocation due two main issues:
+ 1. The function should be async-signal-safe and a running on a signal
+ handler with a fail outcome might lead to malloc bad state.
+ 2. It might be used in a vfork/clone(VFORK) scenario where using
+ malloc also might lead to internal bad state. */
+ int i;
+ char *argv[argc + 1];
+ char **envp;
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i <= argc; i++)
+ argv[i] = va_arg (ap, char *);
+ envp = va_arg (ap, char **);
+ va_end (ap);
+
+ return __execve (path, argv, envp);
}
libc_hidden_def (execle)
diff --git a/posix/execlp.c b/posix/execlp.c
index 6700994..7b84ffa 100644
--- a/posix/execlp.c
+++ b/posix/execlp.c
@@ -17,11 +17,8 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute FILE, searching in the `PATH' environment variable if
it contains no slashes, with all arguments after FILE until a
@@ -29,45 +26,33 @@
int
execlp (const char *file, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
{
- if (i == argv_max)
+ if (argc == INT_MAX)
{
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
+ errno = E2BIG;
+ return -1;
}
-
- argv[i] = va_arg (args, const char *);
+ continue;
}
- va_end (args);
-
- int ret = execvp (file, (char *const *) argv);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ va_end (ap);
+
+ /* Although posix does not state execlp as an async-safe function
+ it can not use malloc to allocate the arguments since it might
+ be used in a vfork scenario and it may lead to malloc internal
+ bad state. */
+ int i;
+ char *argv[argc + 1];
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i < argc; i++)
+ argv[i] = va_arg (ap, char *);
+ argv[i] = NULL;
+ va_end (ap);
+
+ return __execvpe (file, argv, __environ);
}
libc_hidden_def (execlp)
--
1.9.1
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 3/3] posix: New Linux posix_spawn{p} implementation
2016-02-26 13:57 ` [PATCH 3/3] posix: New Linux posix_spawn{p} implementation Adhemerval Zanella
@ 2016-02-26 17:33 ` Joseph Myers
2016-02-26 20:07 ` Adhemerval Zanella
2016-02-26 20:49 ` Paul Eggert
1 sibling, 1 reply; 28+ messages in thread
From: Joseph Myers @ 2016-02-26 17:33 UTC (permalink / raw)
To: Adhemerval Zanella; +Cc: libc-alpha
On Fri, 26 Feb 2016, Adhemerval Zanella wrote:
> There is an inherent race condition in pipe2 usage for architectures
> that do not support the syscall directly. In such cases the a pipe plus
But we don't have any such architectures after the increase in the minimum
kernel for non-x86/x86_64. The patch should be simplified accordingly.
(__ASSUME_PIPE2 is still relevant in non-Linux-specific files, so can't be
removed completely from glibc.)
--
Joseph S. Myers
joseph@codesourcery.com
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-26 14:19 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
@ 2016-02-26 19:11 ` Paul Eggert
2016-02-26 19:44 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-26 19:11 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
On 02/26/2016 05:56 AM, Adhemerval Zanella wrote:
> + for (i = 1; i < argc; i++)
> + argv[i] = va_arg (ap, char *);
> + argv[i] = NULL;
Change "i < argc" to "i <= argc" and remove the "argv[i] = NULL;", as
that's a bit simpler and faster.
> + int i;
> + char *argv[argc + 1];
> + char **envp;
> + va_start (ap, arg);
> + argv[0] = (char *) arg;
> + for (i = 1; i <= argc; i++)
This sort of thing has undefined behavior on x86-64 if argc == INT_MAX.
You can fix this by changing the type of argc and of i from int to
ptrdiff_t.
> + if (argc == INT_MAX)
> {
> + errno = E2BIG;
> + return -1;
> }
Doesn't that have undefined behavior? My impression from C11 is that
since the function has called va_start it must call va_end before returning.
> + continue;
> }
That 'continue;' is redundant and should be removed.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 2/3] posix: execvpe cleanup
2016-02-26 13:57 ` [PATCH 2/3] posix: execvpe cleanup Adhemerval Zanella
@ 2016-02-26 19:40 ` Paul Eggert
2016-02-26 22:22 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-26 19:40 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
This one has similar problems with int vs ptrdiff_t. Also:
On 02/26/2016 05:56 AM, Adhemerval Zanella wrote:
> for (const char *p = path; ; p = subp)
> {
> if (errno == ENOEXEC)
> maybe_script_execute (buffer, argv, envp);
This has O(P*C) behavior, where P is the length of the path and C is the
argument count. How about changing it to have O(P + C) behavior instead,
by allocating the substitute argv in __execvpe, and reusing it each time
through the loop? (Admittedly the current code also has this performance
bug.)
> /* Construct an argument list for the shell. */
> char *new_argv[argc];
This should be "argc +1", not "argc". Shouldn't we have a test case to
catch bugs like this?
> new_argv[0] = (char *) _PATH_BSHELL;
> new_argv[1] = (char *) file;
> while (argc > 1)
> {
> new_argv[argc] = argv[argc - 1];
> --argc;
> }
This mishandles the case where argc == 1, which is possible with an
empty argument vector. The resulting argument vector is not
null-terminated. (Admittedly the current code also has this bug.) I
suppose we should have a test case for this.
> bool got_eacces = false;
> for (const char *p = path; ; p = subp)
> {
> char buffer[path_len + file_len + 1];
Declare 'buffer' just before the loop starts, not in the loop body. That
will make the code run a bit faster, as the buffer will be allocated and
deallocated only once. This is OK since (path_len + file_len + 1) does
not change.
> /* Set current path considered plus a '/'. */
> memcpy (buffer, p, subp - p);
> buffer[subp - p] = '/';
> /* And the file to execute. */
> memcpy (buffer + (subp - p) + !!(subp > p), file, file_len + 1);
Shouldn't this be using mempcpy? That should simplify the code. I find
the "!!" ugly and unnecessary; there's nothing wrong with treating a
boolean as an int, and besides, !! on a boolean still gives you a
boolean so what's the point? Something like this, perhaps:
/* Use the current path entry, plus a '/' if nonempty, plus the
file to execute. */
char *pend = mempcpy (buffer, p, subp - p);
*pend = '/';
memcpy (pend + (p < subp), file, file_len + 1);
> + /* Record the we got a 'Permission denied' error. If we end
the -> that
> +# define EXECVP(__file, __argv) execvp (__file, __argv)
No need for the underscores here.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-26 19:11 ` Paul Eggert
@ 2016-02-26 19:44 ` Adhemerval Zanella
2016-02-26 20:13 ` Paul Eggert
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 19:44 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 26-02-2016 15:47, Paul Eggert wrote:
> On 02/26/2016 05:56 AM, Adhemerval Zanella wrote:
>> + for (i = 1; i < argc; i++)
>> + argv[i] = va_arg (ap, char *);
>> + argv[i] = NULL;
>
> Change "i < argc" to "i <= argc" and remove the "argv[i] = NULL;", as that's a bit simpler and faster.
I added to make it explicit, I will change that.
>
>> + int i;
>> + char *argv[argc + 1];
>> + char **envp;
>> + va_start (ap, arg);
>> + argv[0] = (char *) arg;
>> + for (i = 1; i <= argc; i++)
>
> This sort of thing has undefined behavior on x86-64 if argc == INT_MAX. You can fix this by changing the type of argc and of i from int to ptrdiff_t.
>
Indeed, but afaik this code won't execute if argc == INT_MAX (the argument
sanity check will make the function with E2BIG).
>> + if (argc == INT_MAX)
>> {
>> + errno = E2BIG;
>> + return -1;
>> }
>
> Doesn't that have undefined behavior? My impression from C11 is that since the function has called va_start it must call va_end before returning.
>
Yes, I will remove it.
>> + continue;
>> }
>
> That 'continue;' is redundant and should be removed.
I will remove it.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 3/3] posix: New Linux posix_spawn{p} implementation
2016-02-26 17:33 ` Joseph Myers
@ 2016-02-26 20:07 ` Adhemerval Zanella
0 siblings, 0 replies; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 20:07 UTC (permalink / raw)
To: Joseph Myers; +Cc: libc-alpha
On 26-02-2016 14:33, Joseph Myers wrote:
> On Fri, 26 Feb 2016, Adhemerval Zanella wrote:
>
>> There is an inherent race condition in pipe2 usage for architectures
>> that do not support the syscall directly. In such cases the a pipe plus
>
> But we don't have any such architectures after the increase in the minimum
> kernel for non-x86/x86_64. The patch should be simplified accordingly.
> (__ASSUME_PIPE2 is still relevant in non-Linux-specific files, so can't be
> removed completely from glibc.)
>
Indeed, I forgot the 3.2 clean up. I think now we can now cleanup the alpha
kernel-features that still have the tests for 2.6.33.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-26 19:44 ` Adhemerval Zanella
@ 2016-02-26 20:13 ` Paul Eggert
2016-02-26 20:18 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-26 20:13 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
On 02/26/2016 11:40 AM, Adhemerval Zanella wrote:
> Indeed, but afaik this code won't execute if argc == INT_MAX (the argument
> sanity check will make the function with E2BIG).
No, because we add 1 to argc after testing that it is not INT_MAX. So
argc can equal INT_MAX after that.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-26 20:13 ` Paul Eggert
@ 2016-02-26 20:18 ` Adhemerval Zanella
0 siblings, 0 replies; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 20:18 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 26-02-2016 17:07, Paul Eggert wrote:
> On 02/26/2016 11:40 AM, Adhemerval Zanella wrote:
>> Indeed, but afaik this code won't execute if argc == INT_MAX (the argument
>> sanity check will make the function with E2BIG).
>
> No, because we add 1 to argc after testing that it is not INT_MAX. So argc can equal INT_MAX after that.
Right, I am assuming you are referring to the potentially overflow in
addition, now the stack allocation. I will change to ptrdiff_t.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 3/3] posix: New Linux posix_spawn{p} implementation
2016-02-26 13:57 ` [PATCH 3/3] posix: New Linux posix_spawn{p} implementation Adhemerval Zanella
2016-02-26 17:33 ` Joseph Myers
@ 2016-02-26 20:49 ` Paul Eggert
2016-02-26 23:47 ` Adhemerval Zanella
1 sibling, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-26 20:49 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
Similar issues with int vs ptrdiff_t, argc + 1, etc.
This patch creates new lines with trailing white space; please avoid
that. (Doesn't git complain about that to you? It does to me.)
> /* To avoid impose hard limits on posix_spawn{p} total number of
> arguments
impose -> imposing
total -> the total
valus. */
values
> /* Add a slack area to child own stack. */
child -> the child's
> clobber due stack spilling). The remaning issue are:
Misspelling of "remaining".
> 1. That no signal handlers must run in child context, to avoid corrupt
corrupt -> corrupting
> a pipe or waitpid (in case or error). The pipe has the advantage of
> allowing the child the signal an exec error. */
the signal -> to signal (or better yet, reword to avoid "signal" since
this doesn't use signals)
> /* Then apply FD_CLOCEXEC if it is supported in the pipe call case. */
Misspelled "FD_CLOEXEC".
> /* Try pipe2 even if __ASSUME_PIPE2 is not define and returning an error
> iff the call returns ENOSYS. */
define and returning -> defined and return
> if (__have_pipe2 > 0)
> return r;
This code is unnecessary and can be removed.
> if (__have_pipe2 < 0)
> if (__pipe (pipe_fds) < 0)
> return -1;
>
> /* Then apply FD_CLOCEXEC if it is supported in the pipe call case. */
> if (__have_pipe2 < 0)
> {
> if ((r = __fcntl (pipe_fds[0], F_SETFD, FD_CLOEXEC)) == -1
> || (r = __fcntl (pipe_fds[1], F_SETFD, FD_CLOEXEC)) == -1)
> {
> close_not_cancel (pipe_fds[0]);
> close_not_cancel (pipe_fds[1]);
> return r;
> }
> }
This tests __have_pipe2 twice, whereas it should test it just once.
to be called explicity using /bin/sh (_PATH_BSHELL). */
Misspelled "explicitly".
> {
> if (xflags & SPAWN_XFLAGS_USE_PATH)
> return __spawnix (pid, file, acts, attrp, argv, envp, xflags,
> __execvpe);
> return __spawnix (pid, file, acts, attrp, argv, envp, xflags, __execve);
> }
Put the if-then-else inside the __spawnix call, to avoid repetition.
Something like:
return __spawnix (pid, file, acts, attrp, argv, envp, xflags,
xflags & SPAWN_XFLAGS_USE_PATH ?
__execvpe : __execve);
> const int prot = (PROT_READ | PROT_WRITE
> | ((GL (dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
>
> /* Add a slack area to child own stack. */
> const size_t argv_size = (argc * sizeof (void *)) + 512;
> const size_t stack_size = ALIGN_UP (argv_size, GLRO(dl_pagesize));
There is typically no need for locals to be declared "const". We can
easily see that they are not changed by reading the code, and the
"const" makes the declaration a bit harder to read.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 2/3] posix: execvpe cleanup
2016-02-26 19:40 ` Paul Eggert
@ 2016-02-26 22:22 ` Adhemerval Zanella
2016-02-27 23:18 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 22:22 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 26-02-2016 16:38, Paul Eggert wrote:
> This one has similar problems with int vs ptrdiff_t. Also:
>
> On 02/26/2016 05:56 AM, Adhemerval Zanella wrote:
>> for (const char *p = path; ; p = subp)
>> {
>> if (errno == ENOEXEC)
>> maybe_script_execute (buffer, argv, envp);
>
> This has O(P*C) behavior, where P is the length of the path and C is the argument count. How about changing it to have O(P + C) behavior instead, by allocating the substitute argv in __execvpe, and reusing it each time through the loop? (Admittedly the current code also has this performance bug.)
>
I do not oppose, although I would like to focus on fixing the usability and
conformance bugs first and set the performance goal as possible future
improvement. I will add a comment about this possible optimization.
>> /* Construct an argument list for the shell. */
>> char *new_argv[argc];
>
> This should be "argc +1", not "argc". Shouldn't we have a test case to catch bugs like this?
Indeed I will change that. I add a testcase.
>
>> new_argv[0] = (char *) _PATH_BSHELL;
>> new_argv[1] = (char *) file;
>> while (argc > 1)
>> {
>> new_argv[argc] = argv[argc - 1];
>> --argc;
>> }
>
> This mishandles the case where argc == 1, which is possible with an empty argument vector. The resulting argument vector is not null-terminated. (Admittedly the current code also has this bug.) I suppose we should have a test case for this.
>
I will fix that.
>> bool got_eacces = false;
>> for (const char *p = path; ; p = subp)
>> {
>> char buffer[path_len + file_len + 1];
>
> Declare 'buffer' just before the loop starts, not in the loop body. That will make the code run a bit faster, as the buffer will be allocated and deallocated only once. This is OK since (path_len + file_len + 1) does not change.
>
I will change that.
>> /* Set current path considered plus a '/'. */
>> memcpy (buffer, p, subp - p);
>> buffer[subp - p] = '/';
>> /* And the file to execute. */
>> memcpy (buffer + (subp - p) + !!(subp > p), file, file_len + 1);
>
> Shouldn't this be using mempcpy? That should simplify the code. I find the "!!" ugly and unnecessary; there's nothing wrong with treating a boolean as an int, and besides, !! on a boolean still gives you a boolean so what's the point? Something like this, perhaps:
>
> /* Use the current path entry, plus a '/' if nonempty, plus the file to execute. */
> char *pend = mempcpy (buffer, p, subp - p);
> *pend = '/';
> memcpy (pend + (p < subp), file, file_len + 1);
>
>
I do not have a preference regarding to "!!" and your suggestion seems better.
I will change that.
>> + /* Record the we got a 'Permission denied' error. If we end
>
> the -> that
Ack.
>
>> +# define EXECVP(__file, __argv) execvp (__file, __argv)
>
> No need for the underscores here.
OK, I will change that.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 3/3] posix: New Linux posix_spawn{p} implementation
2016-02-26 20:49 ` Paul Eggert
@ 2016-02-26 23:47 ` Adhemerval Zanella
2016-02-28 16:41 ` Paul Eggert
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-26 23:47 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
Thank you very much for the review (and the others too)!
On 26-02-2016 17:18, Paul Eggert wrote:
> Similar issues with int vs ptrdiff_t, argc + 1, etc.
>
> This patch creates new lines with trailing white space; please avoid that. (Doesn't git complain about that to you? It does to me.)
>
>> /* To avoid impose hard limits on posix_spawn{p} total number of arguments
>
> impose -> imposing
> total -> the total
>
> valus. */
>
Ack.
> values
>
>> /* Add a slack area to child own stack. */
>
> child -> the child's
>
Ack.
>> clobber due stack spilling). The remaning issue are:
>
> Misspelling of "remaining".
Ack.
>
>> 1. That no signal handlers must run in child context, to avoid corrupt
>
> corrupt -> corrupting
Ack.
>
>> a pipe or waitpid (in case or error). The pipe has the advantage of
>> allowing the child the signal an exec error. */
>
> the signal -> to signal (or better yet, reword to avoid "signal" since this doesn't use signals)
Ack, I will change to communicate.
>
>> /* Then apply FD_CLOCEXEC if it is supported in the pipe call case. */
>
> Misspelled "FD_CLOEXEC".
>
>> /* Try pipe2 even if __ASSUME_PIPE2 is not define and returning an error
>> iff the call returns ENOSYS. */
> define and returning -> defined and return
>
>> if (__have_pipe2 > 0)
>> return r;
>
> This code is unnecessary and can be removed.
Yes, I already did after Joseph's comments.
>
>> if (__have_pipe2 < 0)
>> if (__pipe (pipe_fds) < 0)
>> return -1;
>>
>> /* Then apply FD_CLOCEXEC if it is supported in the pipe call case. */
>> if (__have_pipe2 < 0)
>> {
>> if ((r = __fcntl (pipe_fds[0], F_SETFD, FD_CLOEXEC)) == -1
>> || (r = __fcntl (pipe_fds[1], F_SETFD, FD_CLOEXEC)) == -1)
>> {
>> close_not_cancel (pipe_fds[0]);
>> close_not_cancel (pipe_fds[1]);
>> return r;
>> }
>> }
>
> This tests __have_pipe2 twice, whereas it should test it just once.
I remove this code.
>
> to be called explicity using /bin/sh (_PATH_BSHELL). */
>
> Misspelled "explicitly".
Ack.
>
>> {
>> if (xflags & SPAWN_XFLAGS_USE_PATH)
>> return __spawnix (pid, file, acts, attrp, argv, envp, xflags, __execvpe);
>> return __spawnix (pid, file, acts, attrp, argv, envp, xflags, __execve);
>> }
>
> Put the if-then-else inside the __spawnix call, to avoid repetition. Something like:
>
> return __spawnix (pid, file, acts, attrp, argv, envp, xflags,
> xflags & SPAWN_XFLAGS_USE_PATH ? __execvpe : __execve);
I will change it.
>
>> const int prot = (PROT_READ | PROT_WRITE
>> | ((GL (dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
>>
>> /* Add a slack area to child own stack. */
>> const size_t argv_size = (argc * sizeof (void *)) + 512;
>> const size_t stack_size = ALIGN_UP (argv_size, GLRO(dl_pagesize));
>
> There is typically no need for locals to be declared "const". We can easily see that they are not changed by reading the code, and the "const" makes the declaration a bit harder to read.
I disagree with this, I see using const on complex expression might help compiler
get logic errors (where the variable is set to a different value) and states
explicit that it should be a constant value. Also, imho I do not see it as
harder to read.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 2/3] posix: execvpe cleanup
2016-02-26 22:22 ` Adhemerval Zanella
@ 2016-02-27 23:18 ` Adhemerval Zanella
2016-02-28 3:31 ` Paul Eggert
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-27 23:18 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 26-02-2016 17:49, Adhemerval Zanella wrote:
>
>
> On 26-02-2016 16:38, Paul Eggert wrote:
>> This one has similar problems with int vs ptrdiff_t. Also:
>>
>> On 02/26/2016 05:56 AM, Adhemerval Zanella wrote:
>>> for (const char *p = path; ; p = subp)
>>> {
>>> if (errno == ENOEXEC)
>>> maybe_script_execute (buffer, argv, envp);
>>
>> This has O(P*C) behavior, where P is the length of the path and C is the argument count. How about changing it to have O(P + C) behavior instead, by allocating the substitute argv in __execvpe, and reusing it each time through the loop? (Admittedly the current code also has this performance bug.)
>>
>
> I do not oppose, although I would like to focus on fixing the usability and
> conformance bugs first and set the performance goal as possible future
> improvement. I will add a comment about this possible optimization.
>
>>> /* Construct an argument list for the shell. */
>>> char *new_argv[argc];
>>
>> This should be "argc +1", not "argc". Shouldn't we have a test case to catch bugs like this?
>
> Indeed I will change that. I add a testcase.
>
>>
>>> new_argv[0] = (char *) _PATH_BSHELL;
>>> new_argv[1] = (char *) file;
>>> while (argc > 1)
>>> {
>>> new_argv[argc] = argv[argc - 1];
>>> --argc;
>>> }
>>
>> This mishandles the case where argc == 1, which is possible with an empty argument vector. The resulting argument vector is not null-terminated. (Admittedly the current code also has this bug.) I suppose we should have a test case for this.
>>
>
> I will fix that.
In fact I think original code is correct. Although execvpe is an GNU extension I
see it should follow the specification of already defined exec* POSIX functions.
And according to POSIX [1], "argv[0] should point to a filename string that
is associated with the process being started by one of the exec functions" (this
differ with man pages with uses the wording 'by convention' to define first
argument should point to process being stated).
So I see that:
char *args[] = { NULL };
execvpe (scriptname, args, NULL)
Which triggers the issue is invalid.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 2/3] posix: execvpe cleanup
2016-02-27 23:18 ` Adhemerval Zanella
@ 2016-02-28 3:31 ` Paul Eggert
2016-02-29 17:45 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-28 3:31 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
Adhemerval Zanella wrote:
> according to POSIX [1], "argv[0] should point to a filename string that
> is associated with the process being started by one of the exec functions"
Sure, but in this context the word "should" is talking about (as POSIX puts it)
"a feature or behavior that is recommended programming practice for optimum
portability." A conforming application is not required to follow the
recommendation, and in order to conform to POSIX glibc must support applications
that do not follow the recommendation but otherwise conform.
My source for the above quote:
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap01.html#tag_01_05_06
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 3/3] posix: New Linux posix_spawn{p} implementation
2016-02-26 23:47 ` Adhemerval Zanella
@ 2016-02-28 16:41 ` Paul Eggert
2016-02-29 18:33 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-28 16:41 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
Adhemerval Zanella wrote:
> I see using const on complex expression might help compiler
> get logic errors (where the variable is set to a different value)
In that case, you should also put "register" in your local declarations too,
right? Something like this:
register const int prot = PROT_READ | PROT_WRITE;
That way, you are also guarded against errors where later code mistakenly
attempts to take the address of 'prot'.
You may think I'm joking, but I have worked with programmers who believe in this
sort of thing, and I have experience with (non-GNU) code using this style. The
problem with this approach is that the attributes get in the way of reading the
code. Attributes like 'const' can make sense for globals, but for local
variables the hassle of maintaining them typically outweighs the meager benefits
of having them. That's certainly the case for this example, anyway.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 2/3] posix: execvpe cleanup
2016-02-28 3:31 ` Paul Eggert
@ 2016-02-29 17:45 ` Adhemerval Zanella
0 siblings, 0 replies; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-29 17:45 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 27-02-2016 20:17, Paul Eggert wrote:
> Adhemerval Zanella wrote:
>> according to POSIX [1], "argv[0] should point to a filename string that
>> is associated with the process being started by one of the exec functions"
>
> Sure, but in this context the word "should" is talking about (as POSIX puts it) "a feature or behavior that is recommended programming practice for optimum portability." A conforming application is not required to follow the recommendation, and in order to conform to POSIX glibc must support applications that do not follow the recommendation but otherwise conform.
>
> My source for the above quote:
>
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap01.html#tag_01_05_06
Fair enough. I also noted uglibc also accepts the empty argument list.
I will change it.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 3/3] posix: New Linux posix_spawn{p} implementation
2016-02-28 16:41 ` Paul Eggert
@ 2016-02-29 18:33 ` Adhemerval Zanella
0 siblings, 0 replies; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-29 18:33 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 28-02-2016 00:24, Paul Eggert wrote:
> Adhemerval Zanella wrote:
>> I see using const on complex expression might help compiler
>> get logic errors (where the variable is set to a different value)
>
> In that case, you should also put "register" in your local declarations too, right? Something like this:
>
> register const int prot = PROT_READ | PROT_WRITE;
>
> That way, you are also guarded against errors where later code mistakenly attempts to take the address of 'prot'.
>
> You may think I'm joking, but I have worked with programmers who believe in this sort of thing, and I have experience with (non-GNU) code using this style. The problem with this approach is that the attributes get in the way of reading the code. Attributes like 'const' can make sense for globals, but for local variables the hassle of maintaining them typically outweighs the meager benefits of having them. That's certainly the case for this example, anyway.
Fair enough, I will change that.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-29 19:10 ` Paul Eggert
@ 2016-02-29 19:35 ` Adhemerval Zanella
0 siblings, 0 replies; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-29 19:35 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 29-02-2016 16:08, Paul Eggert wrote:
> On 02/29/2016 10:33 AM, Adhemerval Zanella wrote:
>> + for (i = 1; i <= argc; i++)
>> + argv[i] = va_arg (ap, char *);
>
> The indenting is off-by-one here, and in some other places like that.
I'll fix these.
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-29 18:34 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
@ 2016-02-29 19:10 ` Paul Eggert
2016-02-29 19:35 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-29 19:10 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
On 02/29/2016 10:33 AM, Adhemerval Zanella wrote:
> + for (i = 1; i <= argc; i++)
> + argv[i] = va_arg (ap, char *);
The indenting is off-by-one here, and in some other places like that.
^ permalink raw reply [flat|nested] 28+ messages in thread
* [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-29 18:33 [PATCH v5 0/3] posix: Execute file function fixes Adhemerval Zanella
@ 2016-02-29 18:34 ` Adhemerval Zanella
2016-02-29 19:10 ` Paul Eggert
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-29 18:34 UTC (permalink / raw)
To: libc-alpha
GLIBC execl{e,p} implementation might use malloc if the total number of
arguments exceed initial assumption size (1024). This might lead to
issues in two situations:
1. execl/execle is stated to be async-signal-safe by POSIX [1]. However
if execl is used in a signal handler with a large argument set (that
may call malloc internally) and if the resulting call fails it might
lead malloc in the program in a bad state.
2. If the functions are used in a vfork/clone(VFORK) situation it also
might issue malloc internal bad state.
This patch fixes it by using stack allocation instead. It also fixes
BZ#19534.
Tested on x86_64.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html
[BZ #19534]
* posix/execl.c (execl): Remove dynamic memory allocation.
* posix/execle.c (execle): Likewise.
* posix/execlp.c (execlp): Likewise.
---
posix/execl.c | 68 ++++++++++++++++++++++----------------------------------
posix/execle.c | 70 +++++++++++++++++++++++-----------------------------------
posix/execlp.c | 66 +++++++++++++++++++++---------------------------------
4 files changed, 86 insertions(+), 125 deletions(-)
diff --git a/posix/execl.c b/posix/execl.c
index 102d19d..a765b43 100644
--- a/posix/execl.c
+++ b/posix/execl.c
@@ -16,58 +16,42 @@
<http://www.gnu.org/licenses/>. */
#include <unistd.h>
+#include <errno.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
-
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until
a NULL pointer and environment from `environ'. */
int
execl (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
+ ptrdiff_t argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
{
- if (i == argv_max)
+ if (argc == INT_MAX)
{
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
+ va_end (ap);
+ errno = E2BIG;
+ return -1;
}
-
- argv[i] = va_arg (args, const char *);
}
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, __environ);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ va_end (ap);
+
+ /* Avoid dynamic memory allocation due two main issues:
+ 1. The function should be async-signal-safe and a running on a signal
+ handler with a fail outcome might lead to malloc bad state.
+ 2. It might be used in a vfork/clone(VFORK) scenario where using
+ malloc also might lead to internal bad state. */
+ ptrdiff_t i;
+ char *argv[argc + 1];
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i <= argc; i++)
+ argv[i] = va_arg (ap, char *);
+ va_end (ap);
+
+ return __execve (path, argv, __environ);
}
libc_hidden_def (execl)
diff --git a/posix/execle.c b/posix/execle.c
index 8edc03a..b292fec 100644
--- a/posix/execle.c
+++ b/posix/execle.c
@@ -17,57 +17,43 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until a NULL pointer,
and the argument after that for environment. */
int
execle (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
+ ptrdiff_t argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
{
- if (i == argv_max)
+ if (argc == INT_MAX)
{
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
+ va_end (ap);
+ errno = E2BIG;
+ return -1;
}
-
- argv[i] = va_arg (args, const char *);
}
-
- const char *const *envp = va_arg (args, const char *const *);
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, (char *const *) envp);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ va_end (ap);
+
+ /* Avoid dynamic memory allocation due two main issues:
+ 1. The function should be async-signal-safe and a running on a signal
+ handler with a fail outcome might lead to malloc bad state.
+ 2. It might be used in a vfork/clone(VFORK) scenario where using
+ malloc also might lead to internal bad state. */
+ ptrdiff_t i;
+ char *argv[argc + 1];
+ char **envp;
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i <= argc; i++)
+ argv[i] = va_arg (ap, char *);
+ envp = va_arg (ap, char **);
+ va_end (ap);
+
+ return __execve (path, argv, envp);
}
libc_hidden_def (execle)
diff --git a/posix/execlp.c b/posix/execlp.c
index 6700994..77ac7d5 100644
--- a/posix/execlp.c
+++ b/posix/execlp.c
@@ -17,11 +17,8 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute FILE, searching in the `PATH' environment variable if
it contains no slashes, with all arguments after FILE until a
@@ -29,45 +26,32 @@
int
execlp (const char *file, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
+ ptrdiff_t argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
{
- if (i == argv_max)
+ if (argc == INT_MAX)
{
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
+ va_end (ap);
+ errno = E2BIG;
+ return -1;
}
-
- argv[i] = va_arg (args, const char *);
}
- va_end (args);
-
- int ret = execvp (file, (char *const *) argv);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ va_end (ap);
+
+ /* Although posix does not state execlp as an async-safe function
+ it can not use malloc to allocate the arguments since it might
+ be used in a vfork scenario and it may lead to malloc internal
+ bad state. */
+ ptrdiff_t i;
+ char *argv[argc + 1];
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i <= argc; i++)
+ argv[i] = va_arg (ap, char *);
+ va_end (ap);
+
+ return __execvpe (file, argv, __environ);
}
libc_hidden_def (execlp)
--
1.9.1
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-25 14:05 ` Adhemerval Zanella
@ 2016-02-25 15:35 ` Zack Weinberg
0 siblings, 0 replies; 28+ messages in thread
From: Zack Weinberg @ 2016-02-25 15:35 UTC (permalink / raw)
To: Adhemerval Zanella; +Cc: Paul Eggert, GNU C Library
On Thu, Feb 25, 2016 at 8:10 AM, Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
> On 25-02-2016 04:27, Paul Eggert wrote:
>>
>> With my "no arbitrary limits" hat on, I noticed that this has
>> undefined behavior if more than INT_MAX arguments are passed to execl.
>
> AFAIK the C standard defines the main entrypoint argc as signed int, so
> I think it is indeed undefined behaviour if you intend to call a program
> with more than INT_MAX arguments.
The C standard does indeed define main's first argument as signed int,
but I don't think that's a sufficient reason to allow exec* to exhibit
UB for too many arguments. POSIX does *not* call this case out as UB.
I think detecting this situation and failing with errno==E2BIG would
be appropriate. E2BIG is already specified as the error code for
exceeding ARG_MAX bytes of argument list + environment.
zw
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-25 8:58 ` Paul Eggert
@ 2016-02-25 14:05 ` Adhemerval Zanella
2016-02-25 15:35 ` Zack Weinberg
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-25 14:05 UTC (permalink / raw)
To: Paul Eggert, libc-alpha
On 25-02-2016 04:27, Paul Eggert wrote:
> Adhemerval Zanella wrote:
>> + int argc;
>> + va_list ap;
>> + va_start (ap, arg);
>> + for (argc = 1; va_arg (ap, const char *); argc++)
>> + continue;
>
> With my "no arbitrary limits" hat on, I noticed that this has undefined behavior if more than INT_MAX arguments are passed to execl. The existing code is no saint in this area (it messes up badly if more than UINT_MAX args are passed), but the new code should not make things worse, and we might as well fix the UINT_MAX bug while we're at it.
>
AFAIK the C standard defines the main entrypoint argc as signed int, so
I think it is indeed undefined behaviour if you intend to call a program
with more than INT_MAX arguments.
> Attached please find a contrived test case illustrating the bug on x86-64. This test succeeds on x86-64 now (in that the program prints "execl: Cannot allocate memory" and exits with status 0) but could crash with the proposed patch. Perhaps you can add this to the glibc test cases while you're at it.
>
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-22 13:03 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
@ 2016-02-25 8:58 ` Paul Eggert
2016-02-25 14:05 ` Adhemerval Zanella
0 siblings, 1 reply; 28+ messages in thread
From: Paul Eggert @ 2016-02-25 8:58 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
[-- Attachment #1: Type: text/plain, Size: 812 bytes --]
Adhemerval Zanella wrote:
> + int argc;
> + va_list ap;
> + va_start (ap, arg);
> + for (argc = 1; va_arg (ap, const char *); argc++)
> + continue;
With my "no arbitrary limits" hat on, I noticed that this has undefined behavior
if more than INT_MAX arguments are passed to execl. The existing code is no
saint in this area (it messes up badly if more than UINT_MAX args are passed),
but the new code should not make things worse, and we might as well fix the
UINT_MAX bug while we're at it.
Attached please find a contrived test case illustrating the bug on x86-64. This
test succeeds on x86-64 now (in that the program prints "execl: Cannot allocate
memory" and exits with status 0) but could crash with the proposed patch.
Perhaps you can add this to the glibc test cases while you're at it.
[-- Attachment #2: big.c --]
[-- Type: text/x-csrc, Size: 758 bytes --]
/* This program assumes x86-64. Use 'ulimit -s 30000000' before running. */
#include <stdio.h>
#include <unistd.h>
int
main (void)
{
/* Number of extra arguments to pass to execl, counting
the trailing NULL. Must be a multiple of 2. */
long n = 2147483648;
char x[] = "";
/* Push the the trailing NULL onto the stack. */
asm ("pushq $0");
/* Push the the trailing arguments onto the stack. */
for (long i = 1; i < n; i++)
asm ("pushq %0" :: "r" (x));
/* Call execl, without a trailing NULL. GCC may warn
about this. */
execl ("/bin/true", "true", x, x, x, x, x, x, x, x);
/* Pop the added arguments off the stack. */
asm ("addq %0, %%rsp" :: "r" (n * sizeof (char *)));
perror ("execl");
_exit (0);
}
^ permalink raw reply [flat|nested] 28+ messages in thread
* [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-22 13:03 [PATCH v3 0/3] posix: Execute file function fixes Adhemerval Zanella
@ 2016-02-22 13:03 ` Adhemerval Zanella
2016-02-25 8:58 ` Paul Eggert
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-22 13:03 UTC (permalink / raw)
To: libc-alpha
GLIBC execl{e,p} implementation might use malloc if the total number of i
arguments exceed initial assumption size (1024). This might lead to
issue in two situations:
1. execl/execle is stated to be async-signal-safe by POSIX [1]. However
if execl is used in a signal handler with a large argument set (that
may call malloc internally) and the resulting call fails, it might
lead malloc in the program in a bad state.
2. If the functions are used in a vfork/clone(VFORK) situation it also
might issue malloc internal bad state.
This patch fixes it by using stack allocation instead. It also fixes
BZ#19534.
Tested on x86_64.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html
[BZ #19534]
* posix/execl.c (execl): Remove dynamic memory allocation.
* posix/execle.c (execle): Likewise.
* posix/execlp.c (execlp): Likewise.
---
posix/Makefile | 2 +-
posix/execl.c | 65 ++++++++++++++++---------------------------------------
posix/execle.c | 66 +++++++++++++++++---------------------------------------
posix/execlp.c | 68 ++++++++++++++++++++--------------------------------------
5 files changed, 70 insertions(+), 138 deletions(-)
diff --git a/posix/Makefile b/posix/Makefile
index 4e90a95..55f4f31 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -221,8 +221,8 @@ CFLAGS-fexecve.os = -fomit-frame-pointer
CFLAGS-execv.os = -fomit-frame-pointer
CFLAGS-execle.os = -fomit-frame-pointer
CFLAGS-execl.os = -fomit-frame-pointer
-CFLAGS-execvp.os = -fomit-frame-pointer
CFLAGS-execlp.os = -fomit-frame-pointer
+CFLAGS-execvp.os = -fomit-frame-pointer
tstgetopt-ARGS = -a -b -cfoobar --required foobar --optional=bazbug \
--none random --col --color --colour
diff --git a/posix/execl.c b/posix/execl.c
index 102d19d..cd40ff8 100644
--- a/posix/execl.c
+++ b/posix/execl.c
@@ -16,58 +16,31 @@
<http://www.gnu.org/licenses/>. */
#include <unistd.h>
+#include <errno.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
-
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until
a NULL pointer and environment from `environ'. */
int
execl (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
- {
- if (i == argv_max)
- {
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
- }
-
- argv[i] = va_arg (args, const char *);
- }
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, __environ);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
+ continue;
+ va_end (ap);
+
+ int i;
+ char *argv[argc + 1];
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i < argc; i++)
+ argv[i] = va_arg (ap, char *);
+ argv[i] = NULL;
+ va_end (ap);
+
+ return __execve (path, argv, __environ);
}
libc_hidden_def (execl)
diff --git a/posix/execle.c b/posix/execle.c
index 8edc03a..17fc1d4 100644
--- a/posix/execle.c
+++ b/posix/execle.c
@@ -17,57 +17,31 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until a NULL pointer,
and the argument after that for environment. */
int
execle (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
- {
- if (i == argv_max)
- {
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
- }
-
- argv[i] = va_arg (args, const char *);
- }
-
- const char *const *envp = va_arg (args, const char *const *);
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, (char *const *) envp);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
+ continue;
+ va_end (ap);
+
+ int i;
+ char *argv[argc + 1];
+ char **envp;
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i <= argc; i++)
+ argv[i] = va_arg (ap, char *);
+ envp = va_arg (ap, char **);
+ va_end (ap);
+
+ return __execve (path, argv, envp);
}
libc_hidden_def (execle)
diff --git a/posix/execlp.c b/posix/execlp.c
index 6700994..0f789af 100644
--- a/posix/execlp.c
+++ b/posix/execlp.c
@@ -17,11 +17,8 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute FILE, searching in the `PATH' environment variable if
it contains no slashes, with all arguments after FILE until a
@@ -29,45 +26,26 @@
int
execlp (const char *file, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
- {
- if (i == argv_max)
- {
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
- }
-
- argv[i] = va_arg (args, const char *);
- }
- va_end (args);
-
- int ret = execvp (file, (char *const *) argv);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
+ continue;
+ va_end (ap);
+
+ /* Although posix does not state execlp as an async-safe function
+ it can not use malloc to allocate the arguments since it might
+ be used in a vfork scenario and it may lead to malloc internal
+ bad state. */
+ int i;
+ char *argv[argc + 1];
+ va_start (ap, arg);
+ argv[0] = (char *) arg;
+ for (i = 1; i < argc; i++)
+ argv[i] = va_arg (ap, char *);
+ argv[i] = NULL;
+ va_end (ap);
+
+ return __execvpe (file, argv, __environ);
}
libc_hidden_def (execlp)
--
1.9.1
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-19 18:05 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
@ 2016-02-20 8:26 ` Mike Frysinger
0 siblings, 0 replies; 28+ messages in thread
From: Mike Frysinger @ 2016-02-20 8:26 UTC (permalink / raw)
To: Adhemerval Zanella; +Cc: libc-alpha
[-- Attachment #1: Type: text/plain, Size: 540 bytes --]
On 19 Feb 2016 16:05, Adhemerval Zanella wrote:
> int
> execl (const char *path, const char *arg, ...)
> {
> ...
> + char *argv[argc+1];
style nit: needs spaces around the +. comes up in this patch more than once.
> + argv[0] = (char*) arg;
space before the *
> int
> execle (const char *path, const char *arg, ...)
> {
> ...
> + va_start (ap, arg);
> + argv[0] = (char*) arg;
> + for (i = 1; i < argc; i++)
> + argv[i] = va_arg (ap, char *);
> + envp = va_arg (ap, char **);
is argv missing a NULL terminator ?
-mike
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply [flat|nested] 28+ messages in thread
* [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}
2016-02-19 18:05 [PATCH v2 0/3] posix: Execute file function fixes Adhemerval Zanella
@ 2016-02-19 18:05 ` Adhemerval Zanella
2016-02-20 8:26 ` Mike Frysinger
0 siblings, 1 reply; 28+ messages in thread
From: Adhemerval Zanella @ 2016-02-19 18:05 UTC (permalink / raw)
To: libc-alpha
GLIBC execl{e,p} implementation might use malloc if the total number of i
arguments exceed initial assumption size (1024). This might lead to
issue in two situations:
1. execl/execle is stated to be async-signal-safe by POSIX [1]. However
if execl is used in a signal handler with a large argument set (that
may call malloc internally) and the resulting call fails, it might
lead malloc in the program in a bad state.
2. If the functions are used in a vfork/clone(VFORK) situation it also
might issue malloc internal bad state.
This patch fixes it by using stack allocation instead. It also fixes
BZ#19534.
Tested on x86_64.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html
[BZ #19534]
* posix/execl.c (execl): Remove dynamic memory allocation.
* posix/execle.c (execle): Likewise.
* posix/execlp.c (execlp): Likewise.
---
posix/execl.c | 65 +++++++++++++++++----------------------------------------
posix/execle.c | 66 ++++++++++++++++++----------------------------------------
posix/execlp.c | 64 +++++++++++++++++---------------------------------------
5 files changed, 66 insertions(+), 138 deletions(-)
diff --git a/posix/execl.c b/posix/execl.c
index 102d19d..8b8a324 100644
--- a/posix/execl.c
+++ b/posix/execl.c
@@ -16,58 +16,31 @@
<http://www.gnu.org/licenses/>. */
#include <unistd.h>
+#include <errno.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
-
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until
a NULL pointer and environment from `environ'. */
int
execl (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
- {
- if (i == argv_max)
- {
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
- }
-
- argv[i] = va_arg (args, const char *);
- }
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, __environ);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
+ continue;
+ va_end (ap);
+
+ int i;
+ char *argv[argc+1];
+ va_start (ap, arg);
+ argv[0] = (char*) arg;
+ for (i = 1; i < argc; i++)
+ argv[i] = va_arg (ap, char *);
+ argv[i] = NULL;
+ va_end (ap);
+
+ return __execve (path, argv, __environ);
}
libc_hidden_def (execl)
diff --git a/posix/execle.c b/posix/execle.c
index 8edc03a..1a0c9ee 100644
--- a/posix/execle.c
+++ b/posix/execle.c
@@ -17,57 +17,31 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute PATH with all arguments after PATH until a NULL pointer,
and the argument after that for environment. */
int
execle (const char *path, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
- {
- if (i == argv_max)
- {
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
- }
-
- argv[i] = va_arg (args, const char *);
- }
-
- const char *const *envp = va_arg (args, const char *const *);
- va_end (args);
-
- int ret = __execve (path, (char *const *) argv, (char *const *) envp);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
+ continue;
+ va_end (ap);
+
+ int i;
+ char *argv[argc+1];
+ char **envp;
+ va_start (ap, arg);
+ argv[0] = (char*) arg;
+ for (i = 1; i < argc; i++)
+ argv[i] = va_arg (ap, char *);
+ envp = va_arg (ap, char **);
+ va_end (ap);
+
+ return __execve (path, argv, envp);
}
libc_hidden_def (execle)
diff --git a/posix/execlp.c b/posix/execlp.c
index 6700994..a0e1859 100644
--- a/posix/execlp.c
+++ b/posix/execlp.c
@@ -17,11 +17,8 @@
#include <unistd.h>
#include <stdarg.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stackinfo.h>
+#include <errno.h>
+#include <sys/param.h>
/* Execute FILE, searching in the `PATH' environment variable if
it contains no slashes, with all arguments after FILE until a
@@ -29,45 +26,22 @@
int
execlp (const char *file, const char *arg, ...)
{
-#define INITIAL_ARGV_MAX 1024
- size_t argv_max = INITIAL_ARGV_MAX;
- const char *initial_argv[INITIAL_ARGV_MAX];
- const char **argv = initial_argv;
- va_list args;
-
- argv[0] = arg;
-
- va_start (args, arg);
- unsigned int i = 0;
- while (argv[i++] != NULL)
- {
- if (i == argv_max)
- {
- argv_max *= 2;
- const char **nptr = realloc (argv == initial_argv ? NULL : argv,
- argv_max * sizeof (const char *));
- if (nptr == NULL)
- {
- if (argv != initial_argv)
- free (argv);
- va_end (args);
- return -1;
- }
- if (argv == initial_argv)
- /* We have to copy the already filled-in data ourselves. */
- memcpy (nptr, argv, i * sizeof (const char *));
-
- argv = nptr;
- }
-
- argv[i] = va_arg (args, const char *);
- }
- va_end (args);
-
- int ret = execvp (file, (char *const *) argv);
- if (argv != initial_argv)
- free (argv);
-
- return ret;
+ int argc;
+ va_list ap;
+ va_start (ap, arg);
+ for (argc = 1; va_arg (ap, const char *); argc++)
+ continue;
+ va_end (ap);
+
+ int i;
+ char *argv[argc+1];
+ va_start (ap, arg);
+ argv[0] = (char*) arg;
+ for (i = 1; i < argc; i++)
+ argv[i] = va_arg (ap, char *);
+ argv[i] = NULL;
+ va_end (ap);
+
+ return __execvpe (file, argv, __environ);
}
libc_hidden_def (execlp)
--
1.9.1
^ permalink raw reply [flat|nested] 28+ messages in thread
end of thread, other threads:[~2016-02-29 19:34 UTC | newest]
Thread overview: 28+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-02-26 13:57 [PATCH 0/3] posix: Execute file function fixes Adhemerval Zanella
2016-02-26 13:57 ` [PATCH 3/3] posix: New Linux posix_spawn{p} implementation Adhemerval Zanella
2016-02-26 17:33 ` Joseph Myers
2016-02-26 20:07 ` Adhemerval Zanella
2016-02-26 20:49 ` Paul Eggert
2016-02-26 23:47 ` Adhemerval Zanella
2016-02-28 16:41 ` Paul Eggert
2016-02-29 18:33 ` Adhemerval Zanella
2016-02-26 13:57 ` [PATCH 2/3] posix: execvpe cleanup Adhemerval Zanella
2016-02-26 19:40 ` Paul Eggert
2016-02-26 22:22 ` Adhemerval Zanella
2016-02-27 23:18 ` Adhemerval Zanella
2016-02-28 3:31 ` Paul Eggert
2016-02-29 17:45 ` Adhemerval Zanella
2016-02-26 14:19 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
2016-02-26 19:11 ` Paul Eggert
2016-02-26 19:44 ` Adhemerval Zanella
2016-02-26 20:13 ` Paul Eggert
2016-02-26 20:18 ` Adhemerval Zanella
-- strict thread matches above, loose matches on Subject: below --
2016-02-29 18:33 [PATCH v5 0/3] posix: Execute file function fixes Adhemerval Zanella
2016-02-29 18:34 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
2016-02-29 19:10 ` Paul Eggert
2016-02-29 19:35 ` Adhemerval Zanella
2016-02-22 13:03 [PATCH v3 0/3] posix: Execute file function fixes Adhemerval Zanella
2016-02-22 13:03 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
2016-02-25 8:58 ` Paul Eggert
2016-02-25 14:05 ` Adhemerval Zanella
2016-02-25 15:35 ` Zack Weinberg
2016-02-19 18:05 [PATCH v2 0/3] posix: Execute file function fixes Adhemerval Zanella
2016-02-19 18:05 ` [PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p} Adhemerval Zanella
2016-02-20 8:26 ` Mike Frysinger
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