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* [binutils-gdb] gdbserver/linux: free process_info_private and arch_process_info when failing to attach
@ 2022-04-22 18:04 Simon Marchi
0 siblings, 0 replies; only message in thread
From: Simon Marchi @ 2022-04-22 18:04 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f551c8ef326a022ec44279e66ed9734692225067
commit f551c8ef326a022ec44279e66ed9734692225067
Author: Simon Marchi <simon.marchi@polymtl.ca>
Date: Fri Apr 22 11:34:54 2022 -0400
gdbserver/linux: free process_info_private and arch_process_info when failing to attach
Running
$ ../gdbserver/gdbserver --once --attach :1234 539436
with ASan while /proc/sys/kernel/yama/ptrace_scope is set to 1 (prevents
attaching) shows that we fail to free some platform-specific objects
tied to the process_info (process_info_private and arch_process_info):
Direct leak of 32 byte(s) in 1 object(s) allocated from:
#0 0x7f6b558b3fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x562eaf15d04a in xcalloc /home/simark/src/binutils-gdb/gdbserver/../gdb/alloc.c:100
#2 0x562eaf251548 in xcnew<process_info_private> /home/simark/src/binutils-gdb/gdbserver/../gdbsupport/poison.h:122
#3 0x562eaf22810c in linux_process_target::add_linux_process_no_mem_file(int, int) /home/simark/src/binutils-gdb/gdbserver/linux-low.cc:426
#4 0x562eaf22d33f in linux_process_target::attach(unsigned long) /home/simark/src/binutils-gdb/gdbserver/linux-low.cc:1132
#5 0x562eaf1a7222 in attach_inferior /home/simark/src/binutils-gdb/gdbserver/server.cc:308
#6 0x562eaf1c1016 in captured_main /home/simark/src/binutils-gdb/gdbserver/server.cc:3949
#7 0x562eaf1c1d60 in main /home/simark/src/binutils-gdb/gdbserver/server.cc:4084
#8 0x7f6b552f630f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Indirect leak of 56 byte(s) in 1 object(s) allocated from:
#0 0x7f6b558b3fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x562eaf15d04a in xcalloc /home/simark/src/binutils-gdb/gdbserver/../gdb/alloc.c:100
#2 0x562eaf2a0d79 in xcnew<arch_process_info> /home/simark/src/binutils-gdb/gdbserver/../gdbsupport/poison.h:122
#3 0x562eaf295e2c in x86_target::low_new_process() /home/simark/src/binutils-gdb/gdbserver/linux-x86-low.cc:723
#4 0x562eaf22819b in linux_process_target::add_linux_process_no_mem_file(int, int) /home/simark/src/binutils-gdb/gdbserver/linux-low.cc:428
#5 0x562eaf22d33f in linux_process_target::attach(unsigned long) /home/simark/src/binutils-gdb/gdbserver/linux-low.cc:1132
#6 0x562eaf1a7222 in attach_inferior /home/simark/src/binutils-gdb/gdbserver/server.cc:308
#7 0x562eaf1c1016 in captured_main /home/simark/src/binutils-gdb/gdbserver/server.cc:3949
#8 0x562eaf1c1d60 in main /home/simark/src/binutils-gdb/gdbserver/server.cc:4084
#9 0x7f6b552f630f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Those objects are deleted by linux_process_target::mourn, but that is
not called if we fail to attach, we only call remove_process. I
initially fixed this by making linux_process_target::attach call
linux_process_target::mourn on failure (before calling error). But this
isn't done anywhere else (including in GDB) so it would just be
confusing to do things differently here.
Instead, add a linux_process_target::remove_linux_process helper method
(which calls remove_process), and call that instead of remove_process in
the Linux target. Move the free-ing of the extra data from the mourn
method to that new method.
Change-Id: I277059a69d5f08087a7f3ef0b8f1792a1fcf7a85
Diff:
---
gdbserver/linux-low.cc | 27 ++++++++++++++++-----------
gdbserver/linux-low.h | 3 +++
2 files changed, 19 insertions(+), 11 deletions(-)
diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index 449c6641f58..8b8614f6ed4 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -440,6 +440,20 @@ linux_process_target::add_linux_process (int pid, int attached)
return proc;
}
+void
+linux_process_target::remove_linux_process (process_info *proc)
+{
+ if (proc->priv->mem_fd >= 0)
+ close (proc->priv->mem_fd);
+
+ this->low_delete_process (proc->priv->arch_private);
+
+ xfree (proc->priv);
+ proc->priv = nullptr;
+
+ remove_process (proc);
+}
+
arch_process_info *
linux_process_target::low_new_process ()
{
@@ -1136,7 +1150,7 @@ linux_process_target::attach (unsigned long pid)
err = attach_lwp (ptid);
if (err != 0)
{
- remove_process (proc);
+ this->remove_linux_process (proc);
std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err);
error ("Cannot attach to process %ld: %s", pid, reason.c_str ());
@@ -1565,8 +1579,6 @@ linux_process_target::detach (process_info *process)
void
linux_process_target::mourn (process_info *process)
{
- struct process_info_private *priv;
-
#ifdef USE_THREAD_DB
thread_db_mourn (process);
#endif
@@ -1576,14 +1588,7 @@ linux_process_target::mourn (process_info *process)
delete_lwp (get_thread_lwp (thread));
});
- /* Freeing all private data. */
- priv = process->priv;
- close (priv->mem_fd);
- low_delete_process (priv->arch_private);
- free (priv);
- process->priv = NULL;
-
- remove_process (process);
+ this->remove_linux_process (process);
}
void
diff --git a/gdbserver/linux-low.h b/gdbserver/linux-low.h
index 4284fb3348a..79be31b8f72 100644
--- a/gdbserver/linux-low.h
+++ b/gdbserver/linux-low.h
@@ -547,6 +547,9 @@ private:
yet. */
process_info *add_linux_process_no_mem_file (int pid, int attached);
+ /* Free resources associated to PROC and remove it. */
+ void remove_linux_process (process_info *proc);
+
/* Add a new thread. */
lwp_info *add_lwp (ptid_t ptid);
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2022-04-22 18:04 [binutils-gdb] gdbserver/linux: free process_info_private and arch_process_info when failing to attach Simon Marchi
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