On Wed, 2018-04-11 at 20:36 +0200, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Pan Bian <[email protected]> > > > [ Upstream commit 35378ce143071c2a6bad4b59a000e9b9f8f6ea67 ] > > In functions cx25840_initialize(), cx231xx_initialize(), and > cx23885_initialize(), the return value of create_singlethread_workqueue() > is used without validation. This may result in NULL dereference and cause > kernel crash. This patch fixes it. [...] > --- a/drivers/media/i2c/cx25840/cx25840-core.c > +++ b/drivers/media/i2c/cx25840/cx25840-core.c > @@ -420,11 +420,13 @@ static void cx25840_initialize(struct i2 > INIT_WORK(&state->fw_work, cx25840_work_handler); > init_waitqueue_head(&state->fw_wait); > q = create_singlethread_workqueue("cx25840_fw"); > - prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE); > - queue_work(q, &state->fw_work); > - schedule(); > - finish_wait(&state->fw_wait, &wait); > - destroy_workqueue(q); > + if (q) { > + prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE); > + queue_work(q, &state->fw_work); > + schedule(); > + finish_wait(&state->fw_wait, &wait); > + destroy_workqueue(q); > + } [...]
Why is the error "handled" by skipping part of the initialisation process? Shouldn't we abort and return an error? Why even create a private workqueue, when we don't do anything that wouldn't work with one of the global workqueues? Why even use a workqueue, if we immediately block waiting for the work to finish? This makes no sense to me. Ben. -- Ben Hutchings Software Developer, Codethink Ltd.
