[Bug sanitizer/77538] segmentation fault: thread sanitizer shadow stack overflow

["coollpe at hotmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77538

--- Comment #2 from peien luo <coollpe at hotmail dot com> ---
(In reply to Dmitry Vyukov from comment #1)
> Hello,
> 
> Shadow stack size was increased several times, and as far as I remember we
> now have a guard page at the end. Please retest with latest gcc/clang, or
> provide a reproducer.

I moved to another box (a virtual machine) to test the new gcc 4.9.4 (because
the other environment is a shared server I can't make many changes on it.)

What I observed is: without tsan, the process runs fine. With tsan turned on,
then it got fully stuck at some point. (D state, cannot attach or trace). I
haven't yet figured out what caused that. Here is a /proc stack when it got
stuck:

$ cat syscall 
35 0x7ffca05f77e0 0x7ffca05f77e0 0x0 0x8 0x7ffca05f78f0 0x7ffca05f7730
0x7ffca05f77d0 0x7f24ff6f349d

$ cat stack 
[<ffffffff81081504>] do_exit+0x1e4/0xa60
[<ffffffff81081dff>] do_group_exit+0x3f/0xa0
[<ffffffff81092c10>] get_signal_to_deliver+0x1d0/0x6d0
[<ffffffff81014417>] do_signal+0x57/0x6c0
[<ffffffff81014adf>] do_notify_resume+0x5f/0xb0
[<ffffffff8164617d>] int_signal+0x12/0x17
[<ffffffffffffffff>] 0xffffffffffffffff