https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109134
Bug ID: 109134
Summary: UBSan signed integer overflow check missing
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: mpolacek 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: ---
Related to bug 109107, but not a dup and my patch doesn't fix this one:
/* { dg-do run { target int32 } } */
/* { dg-options "-fsanitize=signed-integer-overflow" } */
#define INT_MIN (-__INT_MAX__ - 1)
const int a = INT_MIN;
const unsigned int b = 676540;
int d = 1;
__attribute__((noipa)) int
foo ()
{
int c = b - (a - (short) d);
return c;
}
int
main ()
{
foo ();
return 0;
}
With -O0 we give
runtime error: signed integer overflow: -2147483648 - 1 cannot be represented
in type 'int'
but with -O nothing.
We fold
int c = (int) ((unsigned int) b - (unsigned int) ((int) a - (int) (short int)
d));
into
int c = (int) ((unsigned int) (short int) d + 2148160188);
hiding the overflow.
