https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115477
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note with -fsanitize=address we get errors as one would expect:
=================================================================
==1==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7dc0b8500030
at pc 0x0000004012de bp 0x7ffdaad9b020 sp 0x7ffdaad9b018
READ of size 8 at 0x7dc0b8500030 thread T0
#0 0x4012dd in bug(float) (/app/output.s+0x4012dd) (BuildId:
a1b2ef91caf86d8cdb54f9543157d73b050c2ddf)
#1 0x401456 in main (/app/output.s+0x401456) (BuildId:
a1b2ef91caf86d8cdb54f9543157d73b050c2ddf)
#2 0x7dc0ba229d8f (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f) (BuildId:
962015aa9d133c6cbcfb31ec300596d7f44d3348)
#3 0x7dc0ba229e3f in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x29e3f) (BuildId:
962015aa9d133c6cbcfb31ec300596d7f44d3348)
#4 0x401114 in _start (/app/output.s+0x401114) (BuildId:
a1b2ef91caf86d8cdb54f9543157d73b050c2ddf)
Address 0x7dc0b8500030 is located in stack of thread T0 at offset 48 in frame
#0 0x4011e5 in bug(float) (/app/output.s+0x4011e5) (BuildId:
a1b2ef91caf86d8cdb54f9543157d73b050c2ddf)
This frame has 2 object(s):
[48, 52) 'y' (line 5) <== Memory access at offset 48 partially overflows
this variable
[64, 72) 'i' (line 4)
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-buffer-overflow (/app/output.s+0x4012dd)
(BuildId: a1b2ef91caf86d8cdb54f9543157d73b050c2ddf) in bug(float)
Shadow bytes around the buggy address:
0x7dc0b84ffd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b84ffe00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b84ffe80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b84fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b84fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x7dc0b8500000: f1 f1 f1 f1 f1 f1[04]f2 00 f3 f3 f3 00 00 00 00
0x7dc0b8500080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b8500100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b8500180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b8500200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7dc0b8500280: 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
