media: i2c: adv7842: fix possible use-after-free in adv7842_remove()

[ Upstream commit 4a15275b6a18597079f18241c87511406575179a ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/media/i2c/adv7842.c b/drivers/media/i2c/adv7842.c
index cf3b42c9417e75fdc491082c7b01905dbc79c8f9..d7af4fbcb84b3bf9f81ea43a7605c5c264a1712b 100644 (file)
--- a/drivers/media/i2c/adv7842.c
+++ b/drivers/media/i2c/adv7842.c
@@ -3598,7 +3598,7 @@ static int adv7842_remove(struct i2c_client *client)
        struct adv7842_state *state = to_state(sd);
 
        adv7842_irq_enable(sd, false);
-       cancel_delayed_work(&state->delayed_work_enable_hotplug);
+       cancel_delayed_work_sync(&state->delayed_work_enable_hotplug);
        v4l2_device_unregister_subdev(sd);
        media_entity_cleanup(&sd->entity);
        adv7842_unregister_clients(sd);