In the Linux kernel, the following vulnerability has been resolved:

parisc: led: Fix potential null-ptr-deref in start_task()

start_task() calls create_singlethread_workqueue() and not checked the
ret value, which may return NULL. And a null-ptr-deref may happen:

start_task()
    create_singlethread_workqueue() # failed, led_wq is NULL
    queue_delayed_work()
        queue_delayed_work_on()
            __queue_delayed_work()  # warning here, but continue
                __queue_work()      # access wq->flags, null-ptr-deref

Check the ret value and return -ENOMEM if it is NULL.