https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107908
Bug ID: 107908
Summary: A null pointer dereference bug was missed by UBsan at
-O0
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: ---
`gcc-trunk -O0 -fsanitize=undefined -fno-sanitize-recover=all` misses the
NULL-pointer-dereference, while `gcc-trunk -Ox -fsanitize=address
-fno-sanitize-recover=all` (x=1, 2, 3, or s) can detect it.
Compiler explorer: https://godbolt.org/z/x7jo7eYYh
% cat a.c
int a;
int main() {
int *c;
for (int d = 0; d < 1; d++)
*c == (a = 0);
__builtin_printf("%d\n", *c);
}
%
% gcc-tk -O0 -fsanitize=undefined -fno-sanitize-recover=all a.c &&./a.out
1
% gcc-tk -O1 -fsanitize=undefined -fno-sanitize-recover=all -w a.c &&./a.out
a.c:5:5: runtime error: load of null pointer of type 'int'
% gcc-tk -O3 -fsanitize=undefined -fno-sanitize-recover=all -w a.c &&./a.out
a.c:5:5: runtime error: load of null pointer of type 'int'
%
