Integer values that originate from untrusted sources must be guaranteed correct if they are used in any of the following ways:
- as an array index
- in any pointer arithmetic
- as a length or size of an object
- as the bound of an array (for example, a loop counter)
- as an argument to a memory allocation function
- in security critical code
Integer values can be invalidated due to excpetional conditions such as overflow, truncation, or sign error leading to exploitable vulnerabilities. Failure to provide proper range checking can also lead to exploitable vulnerabilities.
Recommendations
INT01-A. Use size_t for all integer values representing the size of an object
INT02-A. Understand integer conversion rules
INT03-A. Use a secure integer library
INT04-A. Enforce limits on integer values originating from untrusted sources
Rules
INT30-C. Do not make assumptions about the type of a bit-field when used in an expression
INT31-C. Ensure that integer conversions do not result in lost or misinterpreted data
INT32-C. Ensure that integer operations do not result in an overflow
INT33-C. Ensure that division and modulo operations do not result in divide-by-zero errors
INT34-C. Ensure integer values are within valid ranges
INT35-C. Do not truncate the return value from a character input function