SEI CERT C Coding Standard

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Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

CERT C++ Secure Coding StandardINT31-CPP. Ensure that integer conversions do not result in lost or misinterpreted data
CERT Oracle Secure Coding Standard for JavaNUM12-J. Ensure conversions of numeric types to narrower types do not result in lost or misinterpreted data
ISO/IEC TR 24772Numeric conversion errors [FLC]
MISRA-C

Rule 10.1 (required): The value of an expression of integer type shall not be implicitly converted to a different underlying type if:
   a) it is not a conversion to a wider integer type of the same signedness, or
   b) the expression is complex, or
   c) the expression is not constant and is a function argument, or
   d) the expression is not constant and is a return expression.
Rule 10.3 (required): The value of a complex expression of integer type may only be cast to a type that is narrower and of the same signedness
   as the underlying type of the expression
Rule 10.5 (required): If the bitwise operators ~ and << are applied to an operand of underlying type unsigned char or unsigned short, the result
   shall be immediately cast to the underlying type of the operand
Rule 12.9 (required): The unary minus operator shall not be applied to an expression whose underlying type is unsigned

MITRE CWECWE-192, Integer coercion error
CWE-197, Numeric truncation error
CWE-681, Incorrect conversion between numeric types

Bibliography

[Dowd 2006]Chapter 6, "C Language Issues" ("Type Conversions," pp. 223–270)
[ISO/IEC 9899:2011]Section 6.3.1.3, "Signed and Unsigned Integers"
[Seacord 2005a]Chapter 5, "Integers"
[Viega 2005]Section 5.2.9, "Truncation Error"
Section 5.2.10, "Sign Extension Error"
Section 5.2.11, "Signed to Unsigned Conversion Error"
Section 5.2.12, "Unsigned to Signed Conversion Error"
[Warren 2002]Chapter 2, "Basics"
[xorl 2009]"CVE-2009-1376: Pidgin MSN SLP Integer Truncation"

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