media: adv7604: fix possible use-after-free in adv76xx_remove()

This driver's remove path calls cancel_delayed_work(). However, that
function does not wait until the work function finishes. This means
that the callback function may still be running after the driver's
remove function has finished, which would result in a use-after-free.

Fix by calling cancel_delayed_work_sync(), which ensures that
the work is properly cancelled, no longer running, and unable
to re-schedule itself.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c
index 10418574a89cf1115de7d36ce9a4c6cd82daf606..3049aa2fd0f01cdabdcc0ae07d0aebdea28a2404 100644 (file)
--- a/drivers/media/i2c/adv7604.c
+++ b/drivers/media/i2c/adv7604.c
@@ -3670,7 +3670,7 @@ static int adv76xx_remove(struct i2c_client *client)
        io_write(sd, 0x6e, 0);
        io_write(sd, 0x73, 0);
 
-       cancel_delayed_work(&state->delayed_work_enable_hotplug);
+       cancel_delayed_work_sync(&state->delayed_work_enable_hotplug);
        v4l2_async_unregister_subdev(sd);
        media_entity_cleanup(&sd->entity);
        adv76xx_unregister_clients(to_state(sd));