PRECISION.LOSS.CALL

Loss of precision during function call

The PRECISION.LOSS checker finds instances in which an implicit cast to a smaller data type during a function call can cause a loss of precision in data.

Vulnerability and risk

Depending on the exact circumstances, this situation is potentially exploitable, for instance if it results in a buffer overflow.

Mitigation and prevention

If the loss of precision cast is intentional, the source of the cast should be masked with an appropriate bitmask. For example:

1
char c = (i & 0xFF);

Vulnerable code example

1
2
3
4
  void foo(unsigned char v);
  void test(unsigned long data){
    foo(data);   
  }

Klocwork flags line 3, in which an unsigned long is converted to an unsigned char.

Related checkers

• PRECISION.LOSS

External guidance

• CWE-192: Integer Coercion Error
• CWE-197: Numeric Truncation Error
• CWE-681: Incorrect Conversion between Numeric Types
• INT31-C:Ensure that integer conversions do not result in lost or misinterpreted data
• STIG-ID:APP3550 Application is vulnerable to integer overflows

Security training

Application security training materials provided by Secure Code Warrior.

• Integer Overflow Training Video - Test your skills with a training example