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Deadlock: Out-of-Sequence Step Value
Time | Thread # |
| Action |
|---|---|---|---|
0 | 3 | 0 | Thread 3 executes first time: predicate is |
1 | 2 | 0 | Thread 2 executes first time: predicate is |
2 | 4 | 0 | Thread 4 executes first time: predicate is |
3 | 0 | 0 | Thread 0 executes first time: predicate is |
4 | 1 | 1 | Thread 1 executes first time: predicate is |
5 | 3 | 2 | Thread 3 wakes up (scheduler choice): predicate is |
6 | — | — | Thread exhaustion! No more threads to run, and a conditional variable signal is needed to wake up the others |
This noncompliant code example violates the liveness property.
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Failing to preserve the thread safety and liveness of a program when using condition variables can lead to indefinite blocking and denial of service (DoS).
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
CON38-C | Low | Unlikely | Medium | P2 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| CodeSonar |
| CONCURRENCY.BADFUNC.CNDSIGNAL | Use of Condition Variable Signal | ||||||
| Cppcheck Premium |
| premium-cert-con38-c | Fully implemented | ||||||
| Helix QAC |
| C1778, C1779 | |||||||
| Klocwork |
| CERT.CONC.UNSAFE_COND_VAR_C | |||||||
| Parasoft C/C++test |
| CERT_C-CON38-a | Use the 'cnd_signal()' function with a unique condition variable | ||||||
| Polyspace Bug Finder |
| CERT C: Rule CON38-C | Checks for multiple threads waiting on same condition variable (rule fully covered) |
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 Oracle Secure Coding Standard for Java | THI02-J. Notify all waiting threads rather than a single thread | Prior to 2018-01-12: CERT: Unspecified Relationship |
Bibliography
| [IEEE Std 1003.1:2013] | XSH, System Interfaces, pthread_cond_broadcastXSH, System Interfaces, pthread_cond_signal |
| [Lea 2000] |
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