Commit 7fc4fdb9 authored Oct 03, 2017 by Sakari Ailus Committed by Mauro Carvalho Chehab Oct 31, 2017

media: v4l: async: Correctly serialise async sub-device unregistration

The check whether an async sub-device is bound to a notifier was performed
without list_lock held, making it possible for another process to
unbind the async sub-device before the sub-device unregistration function
proceeds to take the lock.

Fix this by first acquiring the lock and then proceeding with the check.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

parent fb45f436

drivers/media/v4l2-core/v4l2-async.c

+7 −11

Original line number	Diff line number	Diff line
		@@ -298,20 +298,16 @@ EXPORT_SYMBOL(v4l2_async_register_subdev);

		void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
		{
		struct v4l2_async_notifier *notifier = sd->notifier;

		if (!sd->asd) {
		if (!list_empty(&sd->async_list))
		v4l2_async_cleanup(sd);
		return;
		}

		mutex_lock(&list_lock);

		if (sd->asd) {
		struct v4l2_async_notifier *notifier = sd->notifier;

		list_add(&sd->asd->list, &notifier->waiting);

		if (notifier->unbind)
		notifier->unbind(notifier, sd, sd->asd);
		}

		v4l2_async_cleanup(sd);