According to the C Standard Annex J.2 (133) [ISO/IEC 9899:20112024], the behavior of a program is undefined when
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This rule is also a special case of SIG31-C. Do not access shared objects in signal handlers. The object designated by errno is of static storage duration and is not a volatile sig_atomic_t. As a result, performing any action that would require errno to be set would normally cause undefined behavior 132. The C Standard, 7.14.1.1, paragraph 5, makes a special exception for errno in this case, allowing errno to take on an indeterminate value but specifying that there is no other undefined behavior. This special exception makes it possible to call signal() from within a signal handler without risking undefined behavior, but the handler, and any code executed after the handler returns, must not depend on the value of errno being meaningful.
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Referencing indeterminate values of errno is undefined behavior.
Rule | Severity | Likelihood | Detectable |
|---|
Repairable | Priority | Level | |
|---|---|---|---|
ERR32-C | Low | Unlikely | Yes |
Yes | P3 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| chained-errno-function-calls errno-test-after-wrong-call | Supported | ||||||
| Axivion Bauhaus Suite |
| CertC-ERR32 | |||||||
| Compass/ROSE |
Could detect violations of this rule by looking for signal handlers that themselves call | |||||||||
| Coverity |
| MISRA C 2012 Rule 22.8 MISRA C 2012 Rule 22.9 MISRA C 2012 Rule 22.10 | Implemented | ||||||
| Cppcheck Premium |
| premium-cert-err32-c | |||||||
| Helix QAC |
| C2031 DF4781, DF4782, DF4783 | |||||||
| Klocwork |
| MISRA.INCL.SIGNAL.2012 | |||||||
| LDRA tool suite |
| 44 S | Enhanced enforcement | ||||||
| Parasoft C/C++test |
| CERT_C-ERR32-b | Properly define signal handlers | ||||||
| CERT C: Rule ERR32-C | Checks for misuse of errno in a signal handler (rule fully covered) | |||||||
| RuleChecker |
| chained-errno-function-calls errno-test-after-wrong-call | Supported |
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 |
|---|---|---|
| CERT C Secure Coding Standard | SIG30-C. Call only asynchronous-safe functions within signal handlers | Prior to 2018-01-12: CERT: Unspecified Relationship |
| CERT C Secure Coding Standard | SIG31-C. Do not access shared objects in signal handlers | Prior to 2018-01-12: CERT: Unspecified Relationship |
Bibliography
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