https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107451
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- The bug is in the testcase: gcc -fsanitize=undefined,address -g -o /tmp/pr107451{,.c}; /tmp/pr107451 ================================================================= ==2296364==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffca382d798 at pc 0x00000040148c bp 0x7ffca382d680 sp 0x7ffca382d678 READ of size 8 at 0x7ffca382d798 thread T0 #0 0x40148b in dot /tmp/pr107451.c:9 #1 0x4019f8 in main /tmp/pr107451.c:21 #2 0x7f8c74de858f in __libc_start_call_main (/lib64/libc.so.6+0x2958f) #3 0x7f8c74de8648 in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x29648) #4 0x4010f4 in _start (/tmp/pr107451+0x4010f4) Address 0x7ffca382d798 is located in stack of thread T0 at offset 40 in frame #0 0x401922 in main /tmp/pr107451.c:19 This frame has 2 object(s): [32, 40) 'x' (line 20) <== Memory access at offset 40 overflows this variable [64, 72) 'y' (line 20) 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 /tmp/pr107451.c:9 in dot Shadow bytes around the buggy address: 0x1000146fdaa0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1000146fdab0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1000146fdac0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1000146fdad0: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 0x1000146fdae0: 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00 f1 f1 =>0x1000146fdaf0: f1 f1 00[f2]f2 f2 00 f3 f3 f3 00 00 00 00 00 00 0x1000146fdb00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1000146fdb10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1000146fdb20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1000146fdb30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1000146fdb40: 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 ==2296364==ABORTING x[ix+1] or y[ix+1] when ix is 0 and x is &x in main or y &y in main is an out of bounds access.