[BUG]Mutex leak in remove_from_queue() upon memory allocation failure

[hanqing2025]

Describe the Bug

A mutex leak in remove_from_queue() causes permanent deadlock when memory reallocation fails after removing items. The function acquires a mutex but returns without releasing it on error paths.

Location: obe.c (lines 207-215)

int remove_from_queue(obe_queue_t *queue)
{
    void **tmp;

    pthread_mutex_lock(&queue->mutex);  // Lock acquired
    if (queue->size > 1)
        memmove(&queue->queue[0], &queue->queue[1], sizeof(*queue->queue) * (queue->size-1));
    tmp = realloc(queue->queue, sizeof(*queue->queue) * (queue->size-1));
    queue->size--;
    if (!tmp && queue->size)
    {
        syslog(LOG_ERR, "Malloc failed\n");
        return -1;  // BUG: Returns without unlock!
    }
    queue->queue = tmp;

    pthread_cond_signal(&queue->out_cv);
    pthread_mutex_unlock(&queue->mutex);  // Never reached on error

    return 0;
}

Impact:

• Mutex queue->mutex remains permanently locked after realloc() failure
• All queue operations (add, remove, peek) deadlock permanently
• Encoder pipeline stalls completely → Denial of Service

Execution Flow:

Thread 1:
  → pthread_mutex_lock(&queue->mutex)    // Lock acquired
  → memmove() to shift queue elements    // Success
  → tmp = realloc(...)                    // Memory allocation fails
  → if (!tmp && queue->size)              // Condition TRUE
  → return -1                             // Exit without unlock
  → queue->mutex remains locked forever

Thread 2, 3, ...N:
  → Attempt any queue operation
  → pthread_mutex_lock(&queue->mutex)    // BLOCKS permanently
  → Complete deadlock state

CWE Classification:

• CWE-667: Improper Locking
• CWE-833: Deadlock

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I would appreciate it if you could review and confirm this potential issue. Thank you for your time and for maintaining this project!