* [PATCH 1/2] Add test to check GDB handles dlopen of /proc/self/fd/[num] correctly
2022-10-17 19:38 [PATCH 0/2][PR < shlibs/29586>] GDB hangs when trying to resolve memory mapped shared libraries of an inferior under /proc/self/fd/* Asaf Fisher
@ 2022-10-17 19:38 ` Asaf Fisher
2022-10-17 19:38 ` [PATCH 2/2] Make GDB resolve dlopen of memory mapped shared libraries Asaf Fisher
1 sibling, 0 replies; 5+ messages in thread
From: Asaf Fisher @ 2022-10-17 19:38 UTC (permalink / raw)
To: gdb-patches; +Cc: Asaf Fisher
This test checks that GDB handles correctly paths in the form of
`/proc/self/...` when inferior dlopen them.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29586
---
gdb/testsuite/gdb.base/solib-proc-self.cc | 72 ++++++++++++++++++
gdb/testsuite/gdb.base/solib-proc-self.exp | 86 ++++++++++++++++++++++
2 files changed, 158 insertions(+)
create mode 100644 gdb/testsuite/gdb.base/solib-proc-self.cc
create mode 100644 gdb/testsuite/gdb.base/solib-proc-self.exp
diff --git a/gdb/testsuite/gdb.base/solib-proc-self.cc b/gdb/testsuite/gdb.base/solib-proc-self.cc
new file mode 100644
index 00000000000..dc0b446d53c
--- /dev/null
+++ b/gdb/testsuite/gdb.base/solib-proc-self.cc
@@ -0,0 +1,72 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2007-2022 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#include <sys/mman.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <vector>
+#include <unistd.h>
+
+#ifdef __WIN32__
+#include <windows.h>
+#define dlopen(name, mode) LoadLibrary (name)
+#define dlclose(handle) FreeLibrary (handle)
+#define dlerror() "an error occurred"
+#else
+#include <dlfcn.h>
+#endif
+
+int main()
+{
+ void *handle;
+ /* Read the so's content to a buffer */
+ std::ifstream read_so_file = std::ifstream(SHLIB_NAME);
+ read_so_file.seekg(0, std::ios::end);
+ std::streamsize size = read_so_file.tellg();
+ read_so_file.seekg(0, std::ios::beg);
+ std::vector<char> buffer(size);
+ if (!read_so_file.read(buffer.data(), size))
+ {
+ fprintf (stderr, "Failed to load solib\n");
+ exit(1);
+ }
+
+ int mem_fd = memfd_create("test", 0);
+
+ /* Write the so's data to the memory mapped file. */
+ write(mem_fd, buffer.data(), buffer.size());
+
+ /* Generate the /proc/self/fd/[num] path */
+ std::string prof_self_fd_path; /* break-here */
+ std::stringstream prof_self_fd_path_stream = std::stringstream(prof_self_fd_path);
+ prof_self_fd_path_stream << "/proc/self/fd/" << mem_fd;
+
+ /* Call dlopen on it */
+ handle = dlopen (prof_self_fd_path_stream.str().c_str(), RTLD_LAZY);
+ if (!handle)
+ {
+ fprintf (stderr, "%s\n", dlerror ());
+ exit (1);
+ }
+ /* YAY it worked */
+ dlclose (handle);
+
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.base/solib-proc-self.exp b/gdb/testsuite/gdb.base/solib-proc-self.exp
new file mode 100644
index 00000000000..b59ba357492
--- /dev/null
+++ b/gdb/testsuite/gdb.base/solib-proc-self.exp
@@ -0,0 +1,86 @@
+# Copyright 2007-2022 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+# Test connecting and disconnecting at shared library events.
+
+if {[skip_shlib_tests]} {
+ untested "could not run to main"
+ return 0
+}
+
+standard_testfile .cc
+
+# Chose random lib
+set libfile so-disc-shr
+set libsrc "${srcdir}/${subdir}/${libfile}.c"
+set libname "${libfile}.so"
+set libobj [standard_output_file ${libname}]
+
+# Compile the shared lib
+if { [gdb_compile_shlib $libsrc $libobj {debug}] != ""} {
+ return -1
+}
+
+# Compile test
+if [ prepare_for_testing "failed to prepare" $testfile $srcfile "list shlib_load debug c++ additional_flags=-DSHLIB_NAME=\"${libobj}\"" ] {
+ return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+gdb_load_shlib $libobj
+
+if ![runto_main] then {
+ return 0
+}
+
+# Get inferior's PID for later
+set inferior_pid -1
+gdb_test_multiple "info inferior 1" "get inferior pid" {
+ -re "process (\[0-9\]*).*$gdb_prompt $" {
+ set inferior_pid $expect_out(1,string)
+ pass $gdb_test_name
+ }
+}
+
+# Turn on the solib-events so we can see that gdb resolves everything correctly
+gdb_test_no_output "set stop-on-solib-events 1"
+
+# I use this breakpoint to get the memory mapped fd.
+gdb_breakpoint [gdb_get_line_number "break-here"]
+gdb_continue_to_breakpoint "break-here" ".* break-here .*"
+
+set msg "Getting MEMFD"
+set memfd ""
+gdb_test_multiple "p mem_fd" $msg {
+ -re "\\\$$decimal = (\[^\r\n\]*)\r\n$gdb_prompt $" {
+ set memfd $expect_out(1,string)
+ pass $msg
+ }
+}
+
+gdb_test "continue" "Stopped due to shared library event.*" "continue to load"
+
+# Check if inferior resolved the /proc/self/fd/[num] to /proc/[pid]/fd/[num]
+set msg "Inferior's /proc/self resolving $inferior_pid $memfd"
+set inferior_proc_self_path ""
+gdb_test_multiple "continue" $msg {
+ -re "Attempting to replace `self` with inferior's PID. -> (\/proc\/$inferior_pid\/fd\/$memfd\[^\r\n\]*)\r\n.*$gdb_prompt $" {
+ set inferior_proc_self_path $expect_out(1,string)
+ pass $msg
+ }
+}
--
2.38.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 2/2] Make GDB resolve dlopen of memory mapped shared libraries
2022-10-17 19:38 [PATCH 0/2][PR < shlibs/29586>] GDB hangs when trying to resolve memory mapped shared libraries of an inferior under /proc/self/fd/* Asaf Fisher
2022-10-17 19:38 ` [PATCH 1/2] Add test to check GDB handles dlopen of /proc/self/fd/[num] correctly Asaf Fisher
@ 2022-10-17 19:38 ` Asaf Fisher
2022-10-21 10:50 ` Alexandra Petlanova Hajkova
1 sibling, 1 reply; 5+ messages in thread
From: Asaf Fisher @ 2022-10-17 19:38 UTC (permalink / raw)
To: gdb-patches; +Cc: Asaf Fisher
Introduced `check_proc_self_file` that checks if a path used by
inferior in dlopen is in the form of `/proc/self/...` and if so resolves
it to `/proc/[pid]/...`
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29586
---
gdb/solib-svr4.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 56 insertions(+), 2 deletions(-)
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index 7e83819a03d..231a4fb40e5 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -34,6 +34,7 @@
#include "regcache.h"
#include "gdbthread.h"
#include "observable.h"
+#include "gdbsupport/pathstuff.h"
#include "solist.h"
#include "solib.h"
@@ -46,6 +47,9 @@
#include "gdb_bfd.h"
#include "probe.h"
+#define SLASH_SELF "/self"
+#define PROC_SELF "/proc" SLASH_SELF
+
static struct link_map_offsets *svr4_fetch_link_map_offsets (void);
static int svr4_have_link_map_offsets (void);
static void svr4_relocate_main_executable (void);
@@ -1187,6 +1191,54 @@ svr4_default_sos (svr4_info *info)
return newobj;
}
+/* Check and fix a cenerio where the so path that we extract has a path to
+ /proc/self e.g. /proc/self/fd/[fd_num] If inferior dlopen a path that has
+ /proc/self, GDB must not open it directly becuase the files in /proc/self are
+ unique for each process. Instead we resolve /proc/self to
+ /proc/[inferior_pid]. This change will give GDB the correct path */
+
+static size_t check_proc_self_file(char *so_name, char *normalized_so_name,
+ size_t out_normalized_so_name_len) {
+ /* We dont want a path with /../ yak. */
+ gdb::unique_xmalloc_ptr<char> normalized_path_obj = gdb_realpath(so_name);
+ gdb::string_view normalized_path = gdb::string_view(
+ normalized_path_obj.get(),
+ std::min(strlen(normalized_path_obj.get()), out_normalized_so_name_len));
+
+ /* Is the path really a /proc/self? */
+ if (0 != normalized_path.rfind(PROC_SELF, 0)) return 0;
+
+ /* Lets get the part of the path after /proc/self e.g. /proc/self/fd -> /fd */
+ size_t slash_self_index = normalized_path.rfind(SLASH_SELF);
+ if (std::string::npos == slash_self_index) return 0;
+ size_t after_self_index = slash_self_index + strlen(SLASH_SELF);
+ gdb::string_view after_self_path = normalized_path.substr(after_self_index);
+
+ /* Get inferior path */
+ int inferior_pid = inferior_ptid.pid();
+ std::string inferior_procfs_path = string_printf("/proc/%d", inferior_pid);
+
+ /* Check if there's enoght space in the out buffer for the normalized path. */
+ size_t normalized_so_name_length =
+ inferior_procfs_path.length() + after_self_path.length();
+ if (out_normalized_so_name_len < normalized_so_name_length) return 0;
+
+ /* Build the full path */
+ inferior_procfs_path.append(std::string(after_self_path));
+
+ warning(_("Detected loaded library (%s) from /proc/self.\nAttempting to "
+ "replace `self` with inferior's PID. -> %s"),
+ normalized_path.begin(), inferior_procfs_path.c_str());
+
+ auto out_length =
+ std::min(inferior_procfs_path.length(), out_normalized_so_name_len);
+
+ /* Copy the new path to the out buffer */
+ strncpy(normalized_so_name, inferior_procfs_path.c_str(), out_length);
+
+ return out_length;
+}
+
/* Read the whole inferior libraries chain starting at address LM.
Expect the first entry in the chain's previous entry to be PREV_LM.
Add the entries to the tail referenced by LINK_PTR_PTR. Ignore the
@@ -1246,8 +1298,10 @@ svr4_read_so_list (svr4_info *info, CORE_ADDR lm, CORE_ADDR prev_lm,
warning (_("Can't read pathname for load map."));
continue;
}
-
- strncpy (newobj->so_name, buffer.get (), SO_NAME_MAX_PATH_SIZE - 1);
+ /* Check if path is in /proc/self */
+ if (0 == check_proc_self_file(buffer.get(), newobj->so_name,
+ SO_NAME_MAX_PATH_SIZE - 1))
+ strncpy(newobj->so_name, buffer.get(), SO_NAME_MAX_PATH_SIZE - 1);
newobj->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
strcpy (newobj->so_original_name, newobj->so_name);
--
2.38.0
^ permalink raw reply [flat|nested] 5+ messages in thread