https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102317
Bug ID: 102317
Summary: signed integer overflow sanitizer cannot work well
with -fno-strict-overflow
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: qinzhao at gcc dot gnu.org
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: ---
with the latest gcc12:
$ cat wrap.c
#include <stdio.h>
#include <limits.h>
/* volatile to avoid optimization */
volatile int val;
int main(void)
{
val = INT_MAX;
val += 1;
printf("%d\n", val);
return 0;
}
$ gcc -Wall -O2 -fsanitize=signed-integer-overflow -o wrap wrap.c
$ ./wrap
wrap.c:10:9: runtime error: signed integer overflow: 2147483647 + 1 cannot be
represented in type 'int'
-2147483648
Things work as expected: the overflow is detected and in this warning
mode, the result is a wrap-around.
However, the kernel builds with -fno-strict-overflow which removes
possible undefined behavior, but I still want the sanitizer to catch
this case. Currently it doesn't:
$ gcc -Wall -O2 -fsanitize=signed-integer-overflow -fno-strict-overflow -o wrap
wrap.c
$ ./wrap
-2147483648
