https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108029
Bug ID: 108029
Summary: GCC'ASAN at -O0 failed to detect a memory leak
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: shaohua.li at inf dot ethz.ch
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at
gcc dot gnu.org
Target Milestone: ---
For the following code, GCC trunk at -O0 won't report the memory leak. However,
-O1 and above can successfully report the leak. I checked the assembly code at
-O0, which indeed allocated the memory.
This issue seems to start from GCC-9, GCC-8 can detect the leak at all
optimization levels.
Clang can also detect it at -O0.
Compiler explorer: https://godbolt.org/z/vxoxxY55x
% cat a.c
short a = 1;
int main() {
int *b = malloc(sizeof(int));
for (;a<1;a++) {
int *c = &b[0];
free(b);
int d[1];
int **e = malloc(sizeof &d);
e[0] = &c;
if (a || b[0]) {
*c = 4 ^ *c;
*c = 5;
}
}
}
%
% gcc-tk -O0 -fsanitize=address a.c
% ASAN_OPTIONS=detect_leaks=1 ./a.out
%
% gcc-tk -O1 -fsanitize=address a.c
% ASAN_OPTIONS=detect_leaks=1 ./a.out
=================================================================
==2169810==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 4 byte(s) in 1 object(s) allocated from:
#0 0x7fe9fc8a98bf in __interceptor_malloc
../../../../gcc/libsanitizer/asan/asan_malloc_linux.cpp:69
#1 0x401234 in main
(/zdata/shaoli/sanitizertesting_UseAfterFree/mutate/bugs/gcc/a.out+0x401234)
SUMMARY: AddressSanitizer: 4 byte(s) leaked in 1 allocation(s).
%
