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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hulk Robot <hulkci@huawei.com>,
        Yang Yingliang <yangyingliang@huawei.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 108/184] media: i2c: tda1997: Fix possible use-after-free in tda1997x_remove()
Date:   Mon, 10 May 2021 12:20:02 +0200
Message-Id: <20210510101953.730186051@linuxfoundation.org>
In-Reply-To: <20210510101950.200777181@linuxfoundation.org>
References: <20210510101950.200777181@linuxfoundation.org>
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From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 7f820ab5d4eebfe2d970d32a76ae496a6c286f0f ]

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/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 5e68182001ec..e43d8327b810 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);
 
-- 
2.30.2