Conversions can occur explicitly as the result of a cast or implicitly as required by an operation. While conversions are generally required for the correct execution of a program, they can also lead to lost or misinterpreted data. Conversion of an operand value to a compatible type causes no change to the value or the representation [[ISO/IEC 9899-1999]].
The C99 standard rules define how C compilers handle conversions. These rules include integer promotions, integer conversion rank, and the usual arithmetic conversions.
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Risk Assessment
Misunderstanding integer conversion rules can lead to errors, which in turn can lead to exploitable vulnerabilities.
Recommendation |
Severity |
Likelihood |
Remediation Cost |
Priority |
Level |
|---|---|---|---|---|---|
INT02-A |
2 (medium) |
2 (probable) |
2 (medium) |
P8 |
L2 |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
References
[[Dowd 06]] Chapter 6, "C Language Issues" (Type Conversions 223-270)
[[ISO/IEC 9899-1999]] Section 6.3, "Conversions"
[[ISO/IEC DTR 24772-2007]] Language Vulnerability "XYE Numeric Conversion Errors"
[[MITRE 07]] CWE ID 192
, "Integer Coercion Error"; CWE ID 197, "Numeric Truncation Error"
[[Seacord 05]] Chapter 5, "Integers"
INT01-A. Use size_t for all integer values representing the size of an object 04. Integers (INT) INT03-A. Use a secure integer library