Unsigned value compared against a negative literal
ID |
c.correctness.unsigned_compared_to_negative |
Severity |
low |
Remediation Complexity |
trivial |
Remediation Risk |
low |
Remediation Effort |
low |
Resource |
Numeric Operation |
Language |
C / C++ |
Description
An unsigned value is compared against a negative literal. An unsigned type can never hold a negative value, so this comparison is always true or always false regardless of the unsigned operand — the condition does not test what it appears to test. Compare against 0, or change the operand to a signed type if negative values are actually meaningful here.
Rationale
An unsigned value is compared against a negative literal. An unsigned type can never hold a negative value, so this comparison is always true or always false regardless of the unsigned operand — the condition does not test what it appears to test. Compare against 0, or change the operand to a signed type if negative values are actually meaningful here.
The following code illustrates the pattern detected by this rule:
void configure(unsigned int u, unsigned long ul, int s)
{
// FLAGGED: Unsigned value compared against a negative literal
if (u < -1) { }
// FLAGGED: Unsigned value compared against a negative literal
if (u == -1) { }
// FLAGGED: Unsigned value compared against a negative literal
if (ul > -5) { }
if (u >= 0) { }
if (u > 5) { }
if (s < -1) { }
}Remediation
Follow secure coding practices and review the references below for detailed remediation guidance.