...

signed int result;
signed int si1 = INT_MIN;
signed int si2 = 2;

if( si1> 0){
	if( si2> 0){
		if(si1> (INT_MAX / si2))
		        error_handler("OVERFLOW ERROR", NULL, EOVERFLOW);
	} else {
		if ( si2< (INT_MIN / si1))
			error_handler("OVERFLOW ERROR", NULL, EOVERFLOW);
	}
} else {
	if(si2 > 0){
		if( si1 < (INT_MIN / si2))
			error_handler("OVERFLOW ERROR", NULL, EOVERFLOW);
	} else {
		if( (si1 != 0) && (si2 < (INT_MAX / si1)))
			error_handler("OVERFLOW ERROR", NULL, EOVERFLOW);
	}
}

result = si1 * si2;

Division

Division in C is between two operands of arithmetic type.

Non-compliant Code Example

The following code will result in a signed integer overflow during the division of the signed operands sl1 and sl2. If this behavior is unanticipated, the resulting value may be used to allocate insufficient memory for a subsequent operation or in some other manner which could lead to an exploitable vulnerability.

signed long sl1 = LONG_MIN;
signed long sl2 = -1;
signed long result;

result = sl1 / sl2;

Compliant Solution

The following compliant solution tests the suspect division operation to guarantee there is no possibility of signed overflow. In this particular case, an overflow condition is present and the error_handler() method is invoked.

signed long sl1 = LONG_MIN;
signed long sl2 = -1;
signed long result;

if( (sl2 == 0) || ( (sl1 == LONG_MIN) && (sl2 == -1) ) ){
	error_handler("ERROR OVERFLOW", NULL, EOVERFLOW);
	return 0;
}
result = sl1 / sl2;

Unary Negation

The unary negation operator in C takes an operand of arithmetic type.

Non-compliant Code Example

The following code will result in a signed integer overflow during the unary negation of the signed operand si1. If this behavior is unanticipated, the resulting value may be used to allocate insufficient memory for a subsequent operation or in some other manner which could lead to an exploitable vulnerability.

signed int result;
signed int si1 = INT_MIN;

result = -si1;

Compliant Solution

The following compliant solution tests the suspect negation operation to guarantee there is no possibility of signed overflow. In this particular case, an overflow condition is present and the error_handler() method is invoked.

signed int result;
signed int si1 = INT_MIN;

if (si1== INT_MIN) error_handler("OVERFLOW ERROR", NULL, EOVERFLOW);
return -si1;

Shift Operator

The shift operator in C is between two operands of integer type.

Non-compliant Code Example

The following code will result in an unsigned overflow during the shift operation of the unsigned operands ui1 and ui2. If this behavior is unanticipated, the resulting value may be used to allocate insufficient memory for a subsequent operation or in some other manner which could lead to an exploitable vulnerability.

unsigned int result;
unsigned int ui1 = UINT_MAX;
unsigned int ui2 = sizeof(int)*8;

result = ui1 << ui2;

Compliant Solution

The following compliant solution tests the suspect shift operation to guarantee there is no possibility of unsigned overflow. In this particular case, an overflow condition is present and the error_handler() method is invoked.

unsigned int result;
unsigned int ui1 = UINT_MAX;
unsigned int ui2 = sizeof(int)*8;

if( (ui2 < 0) || (ui2 >= sizeof(int)*8))
	error_handler("OVERFLOW ERROR", NULL, EINVAL);
return ui1 << ui2;