The software unlocks a critical resource more times than intended, leading to an unexpected state in the system.
Extended Description
When software is operating in a concurrent environment and repeatedly unlocks a critical resource, the consequences will vary based on the type of lock, the lock's implementation, and the resource being protected. In some situations such as with semaphores, the resources are pooled and extra calls to unlock will increase the count for the number of available resources, likely resulting in a crash or unpredictable behavior when the system nears capacity.
Attacker provides invalid address to a
memory-reading function, causing a mutex to be unlocked
twice
Potential Mitigations
Phase: Implementation
When locking and unlocking a resource, try to be sure that all control
paths through the code in which the resource is locked one or more times
correspond to exactly as many unlocks. If the software acquires a lock
and then determines it is not able to perform its intended behavior, be
sure to release the lock(s) before waiting for conditions to improve.
Reacquire the lock(s) before trying again.
An alternate way to think about this weakness is as an imbalance between
the number of locks / unlocks in the control flow. Over the course of
execution, if each lock call is not followed by a subsequent call to unlock
in a reasonable amount of time, then system performance may be degraded or
at least operating at less than peak levels if there is competition for the
locks. This entry may need to be modified to reflect these concepts in the
future.
Description
