[Bug]: Improper Mutex Usage in sampleConfigurationObjLock with CVAR_BROADCAST

[koratshail]

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• This issue is replicable using the unmodified sample application

Describe the bug

In the following code snippet from the KVS WebRTC C SDK, a condition variable is broadcast before acquiring the associated mutex, which is incorrect and can lead to missed wakeups or race conditions:
if (IS_VALID_CVAR_VALUE(pSampleConfiguration->cvar) && IS_VALID_MUTEX_VALUE(pSampleConfiguration->sampleConfigurationObjLock)) { CVAR_BROADCAST(pSampleConfiguration->cvar); MUTEX_LOCK(pSampleConfiguration->sampleConfigurationObjLock); MUTEX_UNLOCK(pSampleConfiguration->sampleConfigurationObjLock); }
Issue:

Calling CVAR_BROADCAST before locking the associated mutex (sampleConfigurationObjLock) violates standard POSIX threading best practices. The correct sequence should be:

Lock the mutex.

Modify shared state if needed.

Call CVAR_BROADCAST or CVAR_SIGNAL.

Unlock the mutex.

Failing to follow this sequence may result in the broadcast being missed by threads waiting on the condition variable, leading to unexpected hangs or logic bugs.

Expected Behavior

The sequence should be revised as follows:
if (IS_VALID_CVAR_VALUE(pSampleConfiguration->cvar) && IS_VALID_MUTEX_VALUE(pSampleConfiguration->sampleConfigurationObjLock)) { MUTEX_LOCK(pSampleConfiguration->sampleConfigurationObjLock); CVAR_BROADCAST(pSampleConfiguration->cvar); MUTEX_UNLOCK(pSampleConfiguration->sampleConfigurationObjLock); }

Current Behavior

you can find this above code in [amazon-kinesis-video-streams-webrtc-sdk-c/samples
/Common.c - ](https://github.com/awslabs/amazon-kinesis-video-streams-webrtc-sdk-c/blob/cf817bc5d18f3e4bd499c6b0f9a68c6f4d7e01de/samples/Common.c#L1240C1-L1245C1)

Reproduction Steps

Mention above

WebRTC C SDK version being used

1.12.1

If it was working in a previous version, which one?

No response

Compiler and Version used

10

Operating System and version

Ubuntu 20.04

Platform being used

Embedded Linux