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 bianpan2016@163.com
[ 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.