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From: "stsp at users dot sourceforge.net" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug sanitizer/101476] AddressSanitizer check failed, points out a
 (potentially) non-existing stack error
Date: Tue, 18 Jan 2022 20:24:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101476

--- Comment #5 from Stas Sergeev <stsp at users dot sourceforge.net> ---
Another problem here seems to be
that pthread_cancel() doesn't unpoison
the cancelled thread's stack.
This causes dtors to run on a
randomly poisoned stack, depending
on where the cancellation happened.
That explains the "random" nature of
a crash, and the fact that pthread_cancel()
is in a test-case attached to that ticket,
and in my program as well.

So, the best diagnostic I can come up
with, is that after pthread_cancel() we
have this:
---
#0  __sanitizer::UnsetAlternateSignalStack ()
    at
../../../../libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp:190
#1  0x00007ffff7672f0d in __asan::AsanThread::Destroy (this=3D0x7ffff358e00=
0)
    at ../../../../libsanitizer/asan/asan_thread.cpp:104
#2  0x00007ffff69d2c61 in __GI___nptl_deallocate_tsd ()
    at nptl_deallocate_tsd.c:74
#3  __GI___nptl_deallocate_tsd () at nptl_deallocate_tsd.c:23
#4  0x00007ffff69d5948 in start_thread (arg=3D<optimized out>)
    at pthread_create.c:446
#5  0x00007ffff6a5a640 in clone3 ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
---

And its running on a stack previously
poisoned before pthread_cancel().
Then it detects the access to poisoned
area and is trying to do a stack trace.
But that fails too because the redzone
canary is overwritten.
So all we get is a crash.=