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[RFA] gdbserver crash in gdb/gdbserver/thread.c::thread_search_callback
- From: Joel Brobecker <brobecker at adacore dot com>
- To: gdb-patches at sourceware dot org
- Cc: Pedro Alves <palves at redhat dot com>
- Date: Mon, 21 Dec 2015 19:15:22 +0400
- Subject: [RFA] gdbserver crash in gdb/gdbserver/thread.c::thread_search_callback
- Authentication-results: sourceware.org; auth=none
Connecting GDB to a LynxOS-178 GDBserver causes GDBserver to crash:
% gdbserver :4444 simple_main
Process simple_main created; pid = 19
Listening on port 4444
Remote debugging from host 205.232.38.10
Segmentation fault (core dumped)
We saw this crash on LynxOS and also when using GDBserver on Windows.
The crash happens in thread_search_callback where the function
calls the_target->thread_stopped (via the thread_stopped macro)
without verifying whether the callback is NULL or not.
For the record, the regression was introduced by:
commit a67a9faef0e32886c83611cc7a0ba61e91123063
Date: Mon Nov 30 16:05:26 2015 +0000
Subject: gdbserver:prepare_access_memory: pick another thread
This patch avoids the crash by checking the value of the callback
first, before calling it.
gdb/gdbserver/ChangeLog:
* target.c (thread_search_callback): Add check that
the thread_stopped target callback is not NULL before
calling it.
Does the fix look good to you?
Tested on both Windows (native gdbserver) and LynxOS using
AdaCore's gdb-testsuite.
Thanks,
--
Joel
---
gdb/gdbserver/target.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/gdb/gdbserver/target.c b/gdb/gdbserver/target.c
index b376ce8..59736e5 100644
--- a/gdb/gdbserver/target.c
+++ b/gdb/gdbserver/target.c
@@ -68,7 +68,9 @@ thread_search_callback (struct inferior_list_entry *entry, void *args)
if (ptid_get_pid (entry->id) == ptid_get_pid (s->current_gen_ptid)
&& mythread_alive (ptid_of (thread)))
{
- if (s->stopped == NULL && thread_stopped (thread))
+ if (s->stopped == NULL
+ && the_target->thread_stopped != NULL
+ && thread_stopped (thread))
s->stopped = thread;
if (s->first == NULL)
--
2.1.4