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Mixing bitwise and relational operators in the same full expression can be a sign of a logic error in the expression where a logical operator is usually the intended operator. Do not use the bitwise AND (&), bitwise OR (|), or bitwise XOR (^) operators with an operand of type _Bool, or the result of a relational-expression or equality-expression. If the bitwise operator is intended, it should be indicated with use of a parenthesized expression.

Noncompliant Code Example

In this noncompliant code example, a bitwise & operator is used with the results of an equality-expression:

if (!(getuid() & geteuid() == 0)) { 
  /* ... */ 
} 

Compliant Solution

This compliant solution uses the && operator for the logical operation within the conditional expression:

if (!(getuid() && geteuid() == 0)) {
  /* ... */
}

Risk Assessment

Rule

Severity

Likelihood

Remediation Cost

Priority

Level

EXP46-C

Low

Likely

Low

P9

L2

Automated Detection

Tool

Version

Checker

Description

Astrée
24.04
inappropriate-boolSupported indirectly via MISRA C:2012 Rule 10.1
Axivion Bauhaus Suite

7.2.0

CertC-EXP46
CodeSonar
8.1p0
LANG.TYPE.IOTInappropriate operand type

Coverity

2017.07

CONSTANT_EXPRESSION_RESULT

Partially implemented

Cppcheck
1.66
cert.pyDetected by the addon cert.py
Helix QAC

2024.1

C3344, C4502

C++3709


Klocwork
2024.1
MISRA.LOGIC.OPERATOR.NOT_BOOL
LDRA tool suite
9.7.1
136 SFully Implemented
Parasoft C/C++test
2023.1

CERT_C-EXP46-b

Expressions that are effectively Boolean should not be used as operands to operators other than (&&, ||, !, =, ==, !=, ?:)

PC-lint Plus

1.4

514

Fully supported

Polyspace Bug Finder

R2023b

CERT C: Rule EXP46-C

Checks for bitwise operations on boolean operands (rule fully covered)

PRQA QA-C
Unable to render {include} The included page could not be found.
3344,4502
PRQA QA-C++

4.4

3709
PVS-Studio

7.30

V564, V1015

RuleChecker

24.04

inappropriate-boolSupported indirectly via MISRA C:2012 Rule 10.1

Related Guidelines

Key here (explains table format and definitions)

Taxonomy

Taxonomy item

Relationship

ISO/IEC TR 24772:2013Likely Incorrect Expression [KOA]Prior to 2018-01-12: CERT: Unspecified Relationship
CWE 2.11CWE-480, Use of incorrect operator2017-07-05: CERT: Rule subset of CWE
CWE 2.11CWE-5692017-07-06: CERT: Rule subset of CWE

CERT-CWE Mapping Notes

Key here for mapping notes

CWE-480 and EXP46-C

Intersection( EXP45-C, EXP46-C) = Ø

CWE-480 = Union( EXP46-C, list) where list =

  • Usage of incorrect operator besides s/&/&&/ or s/|/||/

Bibliography

[Hatton 1995]Section 2.7.2, "Errors of Omission and Addition"



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