An object that has volatile-qualified type may be modified in ways unknown to the implementation or have other unknown side effects. Referencing a volatile object by using a non-volatile lvalue is undefined behavior. The C Standard, 6.7.3 4 paragraph 7 [ISO/IEC 9899:20112024], states
If an attempt is made to refer to an object defined with a volatile-qualified type through use of an lvalue with non-volatile-qualified type, the behavior is undefined.
Noncompliant Code Example
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Accessing an object with a volatile-qualified type through a reference with a non-volatile-qualified type is undefined behavior.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
EXP32-C | Low | Likely | Medium | P6 | L2 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| pointer-qualifier-cast-volatile pointer-qualifier-cast-volatile-implicit | Supported indirectly via MISRA C 2012 Rule 11.8 | ||||||
| Axivion Bauhaus Suite |
| CertC-EXP32 | Fully implemented | ||||||
| Clang |
| -Wincompatible-pointer-types-discards-qualifiers |
| Compass/ROSE |
| Coverity |
| MISRA C 2012 Rule 11.8 | Implemented | ||||||
| Cppcheck Premium |
| premium-cert-exp32-c | Partially implemented | ||||||
| GCC |
|
Can detect violations of this rule when the | |||||||||
| Helix QAC |
| C0312, C0562, C0563, C0673, C0674 | Fully implemented | ||||||
| Klocwork |
| CERT.EXPR.VOLATILE.ADDR | Fully implemented | ||||||
| LDRA tool suite |
| 344 S | Partially implemented | ||||||
| Parasoft C/C++test |
| CERT_C-EXP32-a | A cast shall not remove any 'const' or 'volatile' qualification from the type of a pointer or reference |
| Polyspace Bug Finder |
| Checks for cast to pointer that removes const or volatile qualification (rule fully covered) | ||||||||
| RuleChecker |
| pointer-qualifier-cast-volatile pointer-qualifier-cast-volatile-implicit | Supported indirectly via MISRA C 2012 Rule 11.8 |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
Key here (explains table format and definitions)
Taxonomy | Taxonomy item | Relationship |
|---|---|---|
| ISO/IEC TR 24772:2013 | Pointer Casting and Pointer Type Changes [HFC] | Prior to 2018-01-12: CERT: Unspecified Relationship |
| ISO/IEC TR 24772:2013 | Type System [IHN] | Prior to 2018-01-12: CERT: Unspecified Relationship |
| MISRA C:2012 | Rule 11.8 (required) |
| Prior to 2018-01-12: CERT: Unspecified Relationship | ||
| CERT C | EXP55-CPP. Do not access a cv-qualified object through a cv-unqualified type | Prior to 2018-01-12: CERT: Unspecified Relationship |
Bibliography
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