Mutexes are used to protect shared data structures being accessed concurrently. The thread that locks the mutex owns it, and the owning thread should be the only thread to unlock the mutex. If the mutex is destroyed while still in use, there is no more protection of critical sections and shared data are no longer protected. This rule is a specific instance of CON31-C. Do not unlock or destroy another thread's mutex using POSIX threads.
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In this noncompliant code example, a race condition exists between a cleanup and a worker thread. The cleanup thread destroys the lock, which it believes is no longer in use. If there is a heavy load on the system, the worker thread that held the lock can take longer than expected. If the lock is destroyed before the worker thread has completed modifying the shared data, the program may exhibit unexpected behavior.
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The risks of ignoring mutex ownership are similar to the risk of not using mutexes at all, which can result in a violation of data integrity.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
POS48-C |
Medium |
Probable |
High | P4 | L3 |
Automated Detection
Tool | Version | Checker | Description |
|---|
| CodeSonar |
Fortify SCA
| Section |
|---|
V. 5.0 |
| CONCURRENCY.DU | Double Unlock | |||||||
| Helix QAC |
| DF4971, DF4972, DF4981, DF4982 | |||||||
| Parasoft C/C++test |
| CERT_C-POS48-a | Do not destroy another thread's mutex | ||||||
| CERT C: Rule POS48-C | Checks for destruction of locked mutex (rule fully covered) |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
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Key here (explains table format and definitions)
Taxonomy | Taxonomy item | Relationship |
|---|---|---|
| CWE 2.11 | CWE-667, Insufficient locking | 2017-07-10: CERT: Rule subset of CWE |
CERT-CWE Mapping Notes
Key here for mapping notes
CWE-667 and CON31-C/POS48-C
Intersection( CON31-C, POS48-C) = Ø
CWE-667 = Union, CON31-C, POS48-C, list) where list =
- Locking & Unlocking issues besides unlocking another thread’s C mutex or pthread mutex.
Bibliography
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