https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107866
Bug ID: 107866
Summary: gcc trunk's UBSan misses a Nll-pointer-dereference at
-O3.
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 -O3 -fsanitize=undefined` misses the
NULL-pointer-dereference, while `gcc-trunk -Ox -fsanitize=address` (x=0,1, 2,
s) can detect it.
gcc-12 has the same issue.
gcc-11 can detect the bug at all optimization levels.
clang can also detect it at all optimization levels.
Compiler explorer: https://godbolt.org/z/WhrzP6zdf
% cat a.c
int *a;
void main() {
for (;;) {
a = 0;
if (*a)
break;
}
}
%
% gcc-tk -O3 -fsanitize=undefined -fno-sanitize-recover=all a.c &&./a.out
Segmentation fault
% gcc-tk -O2 -fsanitize=undefined -fno-sanitize-recover=all a.c &&./a.out
a.c:5:9: runtime error: load of null pointer of type 'int'
%
