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Include Page
c:INT32-C-c. Ensure that integer multiplication operations do not result in an overflow
c:INT32-C-c. Ensure that integer multiplication operations do not result in an overflow

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Anchor
Division
Division

Division

Division is between two operands of arithmetic type. Overflow can occur during twos-complement signed integer division when the dividend is equal to the minimum (negative) value for the signed integer type and the divisor is equal to -1. Both signed and unsigned division operations are also susceptible to divide-by-zero errors.

Non-Compliant Code Example

This code can result in a signed integer overflow during the division of the signed operands sl1 and sl2 or in a divide-by-zero error. If this behavior is unanticipated, the resulting value may be used to allocate insufficient memory for a subsequent operation or in some other manner that could lead to an exploitable vulnerability.

Code Block

signed long sl1, sl2, result;

result = sl1 / sl2;

Compliant Solution

This compliant solution tests the suspect division operation to guarantee there is no possibility of signed overflow or divide-by-zero errors.

Code Block

signed long sl1, sl2, result;

if ( (sl2 == 0) || ( (sl1 == LONG_MIN) && (sl2 == -1) ) ) {
  /* handle error condition */
}
result = sl1 / sl2;
Include Page
c:INT32-C-d. Ensure that integer division operations do not result in an overflow
c:INT32-C-d. Ensure that integer division operations do not result in an overflow

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Anchor
Unary Negation
Unary Negation

Unary Negation

The unary negation operator takes an operand of arithmetic type. Overflow can occur during twos-complement unary negation when the operand is equal to the minimum (negative) value for the signed integer type.

Non-Compliant Code Example

This code can 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 that could lead to an exploitable vulnerability.

Code Block

signed int si1, result;

result = -si1;

Compliant Solution

This compliant solution tests the suspect negation operation to guarantee there is no possibility of signed overflow.

Code Block

signed int si1, result;

if (si1 == INT_MIN) {
  /* handle error condition */
}
result = -si1;
Include Page
c:INT32-C-e. Ensure that integer unary negation operations do not result in an overflow
c:INT32-C-e. Ensure that integer unary negation operations do not result in an overflow

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Anchor
Left Shift Operator
Left Shift Operator

Left Shift Operator

The left shift operator is between two operands of integer type.

Non-Compliant Code Example

This code can 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 that could lead to an exploitable vulnerability.

Code Block

unsigned int ui1, ui2, result;

result = ui1 << ui2;

Compliant Solution

This compliant solution tests the suspect shift operation to guarantee there is no possibility of unsigned overflow.

Code Block

unsigned int ui1, ui2, result;

if ( (ui2 < 0) || (ui2 >= sizeof(int)*8) ) {
  /* handle error condition */
}
result = ui1 << ui2;
Include Page
c:INT32-C-f. Ensure that integer left shift operations do not result in an overflow
c:INT32-C-f. Ensure that integer left shift operations do not result in an overflow

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Anchor
Right Shift Operator
Right Shift Operator

Right Shift Operator

The shift operator is between two operands of integer type.

Non-Compliant Code Example

This code can 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 that could lead to an exploitable vulnerability.

Code Block

unsigned int ui1, ui2, result;

result = ui1 >> ui2;

Compliant Solution

This compliant solution tests the suspect shift operation to guarantee there is no possibility of unsigned overflow.

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Include Page
c:INT32-C-g. Ensure that integer right shift operations do not result in an overflow
c:INT32-C-g. Ensure that integer right shift operations do not result in an overflow

Exceptions

Unsigned integers can be allowed to exhibit modulo behavior if and only if

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