media: uvcvideo: Fix access to uninitialized fields on probe error

We need to check whether this work we are canceling actually is
initialized.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+2e1ef9188251d9cc7944@syzkaller.appspotmail.com
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/uvc/uvc_ctrl.c

@@ -2345,7 +2345,9 @@ void uvc_ctrl_cleanup_device(struct uvc_device *dev)
 	struct uvc_entity *entity;
 	unsigned int i;
 
-	cancel_work_sync(&dev->async_ctrl.work);
+	/* Can be uninitialized if we are aborting on probe error. */
+	if (dev->async_ctrl.work.func)
+		cancel_work_sync(&dev->async_ctrl.work);
 
 	/* Free controls and control mappings for all entities. */
 	list_for_each_entry(entity, &dev->entities, list) {