linux-kernel - [PATCH -next] media: i2c: tda1997: Fix possible use-after-free in tda1997x

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Message-ID: <20210406134945.2149969-1-yangyingliang@huawei.com>
Date:   Tue, 6 Apr 2021 21:49:45 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>
CC:     <mchehab@...nel.org>, <hverkuil-cisco@...all.nl>
Subject: [PATCH -next] 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@...wei.com>
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
 drivers/media/i2c/tda1997x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/tda1997x.c b/drivers/media/i2c/tda1997x.c
index a09bf0a39d05..89bb7e6dc7a4 100644
--- 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);
 
-- 
2.25.1