CWE-609: Double-Checked Locking
Description
The product uses double-checked locking to access a resource without the overhead of explicit synchronization, but the locking is insufficient.
Double-checked locking refers to the situation where a programmer checks to see if a resource has been initialized, grabs a lock, checks again to see if the resource has been initialized, and then performs the initialization if it has not occurred yet. This should not be done, as it is not guaranteed to work in all languages and on all architectures. In summary, other threads may not be operating inside the synchronous block and are not guaranteed to see the operations execute in the same order as they would appear inside the synchronous block.
- Abstraction
- BaseA weakness specific enough to point to detection and prevention methods.
- Likelihood of exploit
- Not rated by MITRE
- Status
- Draft
Common consequences
- IntegrityOther
Modify Application Data; Alter Execution Logic
Potential mitigations
- Implementation
While double-checked locking can be achieved in some languages, it is inherently flawed in Java before 1.5, and cannot be achieved without compromising platform independence. Before Java 1.5, only use of the synchronized keyword is known to work. Beginning in Java 1.5, use of the volatile keyword allows double-checked locking to work successfully, although there is some debate as to whether it achieves sufficient performance gains. See references.
Related weaknesses
Parent weaknesses
CAPEC attack patterns that exploit it
CWE 4.20 links no CAPEC attack pattern to this weakness.