From: Paul Pluzhnikov <ppluzhnikov@google.com>
To: Andreas Schwab <schwab@suse.de>
Cc: GLIBC Devel <libc-alpha@sourceware.org>
Subject: Re: [patch] Fix path length overflow in realpath (BZ#22786)
Date: Tue, 10 Apr 2018 15:23:00 -0000 [thread overview]
Message-ID: <CALoOobNcYWPr6nn9tktMMQP=kXAyd82-b1YemN4zHvt=PG7_8w@mail.gmail.com> (raw)
In-Reply-To: <mvmefjn5byx.fsf@suse.de>
[-- Attachment #1: Type: text/plain, Size: 269 bytes --]
On Tue, Apr 10, 2018 at 8:15 AM Andreas Schwab <schwab@suse.de> wrote:
> On Apr 10 2018, Paul Pluzhnikov <ppluzhnikov@google.com> wrote:
> > Should I change the test to pass if allocation fails?
> No, unsupported.
Right. Revised patch attached.
--
Paul Pluzhnikov
[-- Attachment #2: glibc-bz22786-20180410.txt --]
[-- Type: text/plain, Size: 3836 bytes --]
diff --git a/stdlib/Makefile b/stdlib/Makefile
index af1643c0c4..d04afd62c8 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -84,7 +84,7 @@ tests := tst-strtol tst-strtod testmb testrand testsort testdiv \
tst-cxa_atexit tst-on_exit test-atexit-race \
test-at_quick_exit-race test-cxa_atexit-race \
test-on_exit-race test-dlclose-exit-race \
- tst-makecontext-align
+ tst-makecontext-align test-bz22786
tests-internal := tst-strtod1i tst-strtod3 tst-strtod4 tst-strtod5i \
tst-tls-atexit tst-tls-atexit-nodelete
@@ -156,6 +156,9 @@ CFLAGS-tst-qsort.c += $(stack-align-test-flags)
CFLAGS-tst-makecontext.c += -funwind-tables
CFLAGS-tst-makecontext2.c += $(stack-align-test-flags)
+# suppress warnings about allocation size.
+CFLAGS-test-bz22786.c += $(+gcc-nowarn)
+
# Run a test on the header files we use.
tests-special += $(objpfx)isomac.out
diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c
index 4135f3f33c..390fb437a8 100644
--- a/stdlib/canonicalize.c
+++ b/stdlib/canonicalize.c
@@ -181,7 +181,7 @@ __realpath (const char *name, char *resolved)
extra_buf = __alloca (path_max);
len = strlen (end);
- if ((long int) (n + len) >= path_max)
+ if (path_max - n <= len)
{
__set_errno (ENAMETOOLONG);
goto error;
diff --git a/stdlib/test-bz22786.c b/stdlib/test-bz22786.c
new file mode 100644
index 0000000000..7b41a0fe5e
--- /dev/null
+++ b/stdlib/test-bz22786.c
@@ -0,0 +1,81 @@
+/* Bug 22786: test for stack overflow in realpath.
+ Copyright (C) 2018 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/>. */
+
+/* This file must be run from within a directory called "stdlib". */
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <support/test-driver.h>
+
+static int
+do_test (void)
+{
+ const char dir[] = "bz22786";
+ const char lnk[] = "bz22786/symlink";
+
+ rmdir (dir);
+ if (mkdir (dir, 0755) != 0 && errno != EEXIST)
+ {
+ printf ("mkdir %s: %m\n", dir);
+ return EXIT_FAILURE;
+ }
+ if (symlink (".", lnk) != 0 && errno != EEXIST)
+ {
+ printf ("symlink (%s, %s): %m\n", dir, lnk);
+ return EXIT_FAILURE;
+ }
+
+ const size_t path_len = (size_t) INT_MAX + 1;
+ char *path = malloc (path_len);
+
+ if (path == NULL)
+ {
+ printf ("malloc (%zu): %m\n", path_len);
+ return EXIT_UNSUPPORTED;
+ }
+
+ /* Construct very long path = "bz22786/symlink/aaaa....." */
+ char *p = mempcpy (path, lnk, sizeof (lnk) - 1);
+ *(p++) = '/';
+ memset (p, 'a', path_len - (path - p) - 2);
+ p[path_len - (path - p) - 1] = '\0';
+
+ /* This call crashes before the fix for bz22786 on 32-bit platforms. */
+ p = realpath (path, NULL);
+
+ if (p != NULL || errno != ENAMETOOLONG)
+ {
+ printf ("realpath: %s (%m)", p);
+ return EXIT_FAILURE;
+ }
+
+ /* Cleanup. */
+ unlink (lnk);
+ rmdir (dir);
+
+ return 0;
+}
+
+#define TEST_FUNCTION do_test
+#include <support/test-driver.c>
next prev parent reply other threads:[~2018-04-10 15:23 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-09 23:02 Paul Pluzhnikov
2018-04-10 0:25 ` Paul Pluzhnikov
2018-04-10 8:08 ` Andreas Schwab
2018-04-10 14:54 ` Paul Pluzhnikov
2018-04-10 15:15 ` Andreas Schwab
2018-04-10 15:23 ` Paul Pluzhnikov [this message]
2018-04-10 15:31 ` Alexander Monakov
2018-04-10 15:44 ` Paul Pluzhnikov
2018-04-10 16:38 ` Alexander Monakov
2018-04-10 16:47 ` Andreas Schwab
2018-04-11 13:32 ` Carlos O'Donell
2018-04-17 21:01 ` Joseph Myers
2018-04-17 23:51 ` Paul Pluzhnikov
2018-04-30 21:42 ` Paul Pluzhnikov
2018-05-08 14:34 ` Paul Pluzhnikov
2018-05-08 14:59 ` Andreas Schwab
2018-05-08 15:11 ` Paul Pluzhnikov
2018-05-08 15:29 ` Andreas Schwab
2018-05-08 15:46 ` Paul Pluzhnikov
2018-05-09 11:11 ` Dmitry V. Levin
2018-05-09 14:23 ` Paul Pluzhnikov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CALoOobNcYWPr6nn9tktMMQP=kXAyd82-b1YemN4zHvt=PG7_8w@mail.gmail.com' \
--to=ppluzhnikov@google.com \
--cc=libc-alpha@sourceware.org \
--cc=schwab@suse.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).