https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107893
Bug ID: 107893
Summary: gcc trunk at -O0 (UBSan) misses a
Null-pointer-dereference
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 -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.
I checked gcc8/9/10/11/12 and they all have this issue.
clang can detect it at all optimization levels.
Compiler explorer: https://godbolt.org/z/85qfdccse
% cat a.c
int main() {
int *a = 0;
(a[1] | a[0]) >> 056;
}
%
% gcc-tk -O0 -fsanitize=undefined -fno-sanitize-recover=all -w a.c &&./a.out
Segmentation fault
% gcc-tk -O1 -fsanitize=undefined -fno-sanitize-recover=all -w a.c &&./a.out
a.c:3:13: runtime error: load of null pointer of type 'int'
%
