media: i2c: tda1997: Fix possible use-after-free in tda1997x_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/tda1997x.c b/drivers/media/i2c/tda1997x.c
index a09bf0a39d05882fc9e847ea41d20c24585a810d..89bb7e6dc7a428e571ce8fe1e432e18d3c92c409 100644 (file)
--- a/drivers/media/i2c/tda1997x.c
+++ b/drivers/media/i2c/tda1997x.c
@@ -2804,7 +2804,7 @@ static int tda1997x_remove(struct i2c_client *client)
        media_entity_cleanup(&sd->entity);
        v4l2_ctrl_handler_free(&state->hdl);
        regulator_bulk_disable(TDA1997X_NUM_SUPPLIES, state->supplies);
-       cancel_delayed_work(&state->delayed_work_enable_hpd);
+       cancel_delayed_work_sync(&state->delayed_work_enable_hpd);
        mutex_destroy(&state->page_lock);
        mutex_destroy(&state->lock);