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

BugLink: https://bugs.launchpad.net/bugs/1928857
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/media/i2c/adv7842.c b/drivers/media/i2c/adv7842.c
index 0855f648416d1d2fcf511efe9afec582235781aa..f7d2b6cd3008b3e4e9bf0e46de05b581cd779aea 100644 (file)
--- a/drivers/media/i2c/adv7842.c
+++ b/drivers/media/i2c/adv7842.c
@@ -3586,7 +3586,7 @@ 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);