https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103978
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is what the trunk gives with full debug info:
=================================================================
==1230123==ERROR: AddressSanitizer: stack-buffer-underflow on address
0x7f69725fedf0 at pc 0x7f69754d0581 bp 0x7f69725fedb0 sp 0x7f69725fe560
WRITE of size 24 at 0x7f69725fedf0 thread T-1
#0 0x7f69754d0580 in __interceptor_sigaltstack
/home/apinski/src/upstream-gcc-git/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:10168
#1 0x7f6975546e3d in __sanitizer::UnsetAlternateSignalStack()
/home/apinski/src/upstream-gcc-git/gcc/libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp:189
#2 0x7f6975536ae4 in __asan::AsanThread::Destroy()
/home/apinski/src/upstream-gcc-git/gcc/libsanitizer/asan/asan_thread.cpp:110
#3 0x7f69752543d0 in __nptl_deallocate_tsd.part.8
(/lib64/libpthread.so.0+0x73d0)
#4 0x7f697525516a in start_thread (/lib64/libpthread.so.0+0x816a)
#5 0x7f6974f86f22 in clone (/lib64/libc.so.6+0xfcf22)
Address 0x7f69725fedf0 is a wild pointer inside of access range of size
0x000000000018.
SUMMARY: AddressSanitizer: stack-buffer-underflow
/home/apinski/src/upstream-gcc-git/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:10168
in __interceptor_sigaltstack
Shadow bytes around the buggy address:
0x0fedae4b7d60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7d70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7d90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7da0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0fedae4b7db0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00[f1]f1
0x0fedae4b7dc0: f1 f1 00 00 f3 f3 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7dd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7de0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7df0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fedae4b7e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==1230123==ABORTING
