When multiple threads can read or modify the same data, use synchronization techniques to avoid software flaws that can lead to security vulnerabilities. Data races can often result in abnormal termination or denial of service, but it is possible for them to result in more serious vulnerabilities. The C Standard, section 5.1.2.45, paragraph 25 35 [ISO/IEC 9899:20112024], says:
The execution of a program contains a data race if it contains two conflicting actions in different threads, at least one of which is not atomic, and neither happens before the other. Any such data race results in undefined behavior.
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This noncompliant code example illustrates Xen Security Advisory CVE-2015-8550 / XSA-155 In this example, the following code is vulnerable to a data race where the integer referenced by ps could be modified by a second thread that ran between the two reads of the variable.
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Recommendation | Severity | Likelihood | Detectable | RepairableRemediation Cost | Priority | Level |
|---|---|---|---|---|---|---|
CON43-C | Medium | Probable | No | NoHigh | P4 | L3 |
Automated Detection
| Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| read_data_race write_data_race | Supported by sound analysis (data race alarm) | ||||||
| CodeSonar |
| CONCURRENCY.DATARACE CONCURRENCY.MAA | Data race Multiple Accesses of Atomic | ||||||
| Coverity |
| MISSING_LOCK (partial) | Implemented | ||||||
| Helix QAC |
| C1765, C1766, C1770, C1771 C++1765, C++1766, C++1770, C++1771 | |||||||
| Parasoft C/C++test |
| CERT_C-CON43-aUsage of functions prone to race is not allowed | Do not use global variable with different locks set | ||||||
| PC-lint Plus |
| 457 | Partially supported: access is detected at the object level (not at the field level) | ||||||
| Polyspace Bug Finder |
| CERT C: Rule CON43-C | Checks for data race (rule fully covered) | ||||||
| V1088 |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
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Taxonomy | Taxonomy item | Relationship |
|---|---|---|
| CWE 2.11 | CWE-366, Race condition within a thread | 2017-07-07: CERT: Exact |
Bibliography
| [ISO/IEC 9899:20112024] | 5.1.2.45, "Multi-threaded Executions and Data Races" 7.17.2, "Initialization" |
| [C99 Rationale 2003] | |
| [Dowd 2006] | Chapter 13, "Synchronization and State" |
| [Plum 2012] | |
| [Seacord 2013] | Chapter 8, "File I/O" |
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