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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 4.14 065/323] media: i2c: adv7842: fix possible use-after-free in adv7842_remove()
Date:   Thu, 20 May 2021 11:19:17 +0200
Message-Id: <20210520092122.334297987@linuxfoundation.org>
In-Reply-To: <20210520092120.115153432@linuxfoundation.org>
References: <20210520092120.115153432@linuxfoundation.org>
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From: Yang Yingliang <yangyingliang@huawei.com>

[ 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>
---
 drivers/media/i2c/adv7842.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/adv7842.c b/drivers/media/i2c/adv7842.c
index dcce8d030e5d..c28bf94a7409 100644
--- a/drivers/media/i2c/adv7842.c
+++ b/drivers/media/i2c/adv7842.c
@@ -3599,7 +3599,7 @@ 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);
-- 
2.30.2