STRONG.TYPE.JOIN.ZEROComparison of strong type with zeroThe STRONG.TYPE family of checkers detects situations in which programmer-enforced strong typing (type-defined abstract types) is broken or ignored, allowing the underlying ANSI type semantics to dominate. The STRONG.TYPE.JOIN.ZERO checker looks for instances of comparison between a strongly typed value and zero using a binary operator. In this rule, zero is defined as any zero constant that has not been cast to a strong type. For example, the checker considers the following to be zero:
The checker considers the following examples not to be zero:
Vulnerability and riskA compiler following the ANSI standard won't report a warning for this sort of issue, as it checks only the underlying types, not the surface, or programmer-defined, types. As a result, it's possible that a logic error can occur. Vulnerable code example
1 typedef float Speed;
2
3 int main() {
4 Speed s;
5 if (s == 0) ;
6 return 0;
7 }
Klocwork flags line 5, indicating that a strongly typed value, s, is compared with zero. Fixed code example
1 typedef float Speed;
2
3 int main() {
4 Speed s;
5 if (s == (Speed) 0) ;
6 return 0;
7 }
In the fixed code, the comparison is made clearly with two strongly typed values. |