https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106503
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> -fsanitize=address sometimes can detect this kind of problems at runtime.
Program returned: 1
=================================================================
==1==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7f9235600030
at pc 0x7f9237ebcc9b bp 0x7ffc8cccff60 sp 0x7ffc8cccf720
READ of size 3 at 0x7f9235600030 thread T0
#0 0x7f9237ebcc9a
(/opt/compiler-explorer/gcc-snapshot/lib64/libasan.so.8+0x4ac9a) (BuildId:
f4e296dda2fcdab4980780e7f32c752a3e412556)
#1 0x7f9237ebcf37 in writev
(/opt/compiler-explorer/gcc-snapshot/lib64/libasan.so.8+0x4af37) (BuildId:
f4e296dda2fcdab4980780e7f32c752a3e412556)
#2 0x401673 in main (/app/output.s+0x401673) (BuildId:
af556f86dec87e7467f73a633f83c822f3afe85a)
#3 0x7f923790b0b2 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x240b2) (BuildId:
9fdb74e7b217d06c93172a8243f8547f947ee6d1)
#4 0x4010ed in _start (/app/output.s+0x4010ed) (BuildId:
af556f86dec87e7467f73a633f83c822f3afe85a)
Address 0x7f9235600030 is located in stack of thread T0 at offset 48 in frame
#0 0x4011b5 in main (/app/output.s+0x4011b5) (BuildId:
af556f86dec87e7467f73a633f83c822f3afe85a)
This frame has 2 object(s):
[48, 52) 'junk' (line 22) <== Memory access at offset 48 is inside this
variable
[64, 384) 'wdata' (line 15)
HINT: this may be a false positive if your program uses some custom stack
unwind mechanism, swapcontext or vfork
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-use-after-scope
(/opt/compiler-explorer/gcc-snapshot/lib64/libasan.so.8+0x4ac9a) (BuildId:
f4e296dda2fcdab4980780e7f32c752a3e412556)
Shadow bytes around the buggy address:
0x0ff2c6ab7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ff2c6ab7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ff2c6ab7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ff2c6ab7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ff2c6ab7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0ff2c6ab8000: f1 f1 f1 f1 f1 f1[f8]f2 00 00 00 00 00 00 00 00
0x0ff2c6ab8010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ff2c6ab8020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ff2c6ab8030: f3 f3 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
0x0ff2c6ab8040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ff2c6ab8050: 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
==1==ABORTING
fooabcbaz
