[PATCH 4.9 039/240] media: adv7604: fix possible use-after-free in adv76xx_remove()

Greg Kroah-Hartman
2021-05-20T11:09:05Z

From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit fa56f5f1fe31c2050675fa63b84963ebd504a5b3 ]

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>
---
drivers/media/i2c/adv7604.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c
index ce6f93074ae0..56b8b7bf759e 100644
--- a/drivers/media/i2c/adv7604.c
+++ b/drivers/media/i2c/adv7604.c
@@ -3541,7 +3541,7 @@ 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));
--
2.30.2