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    Subject[PATCH AUTOSEL 4.20 064/304] media: video-i2c: avoid accessing released memory area when removing driver
    Date
    From: Akinobu Mita <akinobu.mita@gmail.com>

    [ Upstream commit c764da98a600a4b068d25c77164f092f159cecec ]

    The video device release() callback for video-i2c driver frees the whole
    struct video_i2c_data. If there is no user left for the video device
    when video_unregister_device() is called, the release callback is executed.

    However, in video_i2c_remove() some fields (v4l2_dev, lock, and queue_lock)
    in struct video_i2c_data are still accessed after video_unregister_device()
    is called.

    This fixes the use after free by moving the code from video_i2c_remove()
    to the release() callback.

    Fixes: 5cebaac60974 ("media: video-i2c: add video-i2c driver")

    Reviewed-by: Matt Ranostay <matt.ranostay@konsulko.com>
    Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
    Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
    Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
    Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/media/i2c/video-i2c.c | 11 ++++++-----
    1 file changed, 6 insertions(+), 5 deletions(-)

    diff --git a/drivers/media/i2c/video-i2c.c b/drivers/media/i2c/video-i2c.c
    index 4d49af86c15e..ec0758dca2fc 100644
    --- a/drivers/media/i2c/video-i2c.c
    +++ b/drivers/media/i2c/video-i2c.c
    @@ -510,7 +510,12 @@ static const struct v4l2_ioctl_ops video_i2c_ioctl_ops = {

    static void video_i2c_release(struct video_device *vdev)
    {
    - kfree(video_get_drvdata(vdev));
    + struct video_i2c_data *data = video_get_drvdata(vdev);
    +
    + v4l2_device_unregister(&data->v4l2_dev);
    + mutex_destroy(&data->lock);
    + mutex_destroy(&data->queue_lock);
    + kfree(data);
    }

    static int video_i2c_probe(struct i2c_client *client,
    @@ -608,10 +613,6 @@ static int video_i2c_remove(struct i2c_client *client)
    struct video_i2c_data *data = i2c_get_clientdata(client);

    video_unregister_device(&data->vdev);
    - v4l2_device_unregister(&data->v4l2_dev);
    -
    - mutex_destroy(&data->lock);
    - mutex_destroy(&data->queue_lock);

    return 0;
    }
    --
    2.19.1
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