On Thu, Mar 02, 2023 at 05:37:15PM +0800, Zheng Wang wrote:
> In mtk_jpeg_probe, &jpeg->job_timeout_work is bound with
> mtk_jpeg_job_timeout_work. Then mtk_jpeg_dec_device_run
> and mtk_jpeg_enc_device_run may be called to start the
> work.
> If we remove the module which will call mtk_jpeg_remove
> to make cleanup, there may be a unfinished work. The
> possible sequence is as follows, which will cause a
> typical UAF bug.
>
> Fix it by canceling the work before cleanup in the mtk_jpeg_remove
>
> CPU0 CPU1
>
> |mtk_jpeg_job_timeout_work
> mtk_jpeg_remove |
> v4l2_m2m_release |
> kfree(m2m_dev); |
> |
> | v4l2_m2m_get_curr_priv
> | m2m_dev->curr_ctx //use
>
> Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
> ---
> drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
> index 969516a940ba..364513e7897e 100644
> --- a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
> +++ b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
> @@ -1793,7 +1793,7 @@ static int mtk_jpeg_probe(struct platform_device *pdev)
> static int mtk_jpeg_remove(struct platform_device *pdev)
> {
> struct mtk_jpeg_dev *jpeg = platform_get_drvdata(pdev);
> -
> + cancel_delayed_work(&jpeg->job_timeout_work);
The empty line is needed (coding style). Also, this doesn't cancel
the worker if it is already running. This should probably be
cancel_delayed_work_sync(). Even then the question is if it is
possible that new work is queued before the device is unregistered.
Guenter
> pm_runtime_disable(&pdev->dev);
> video_unregister_device(jpeg->vdev);
> v4l2_m2m_release(jpeg->m2m_dev);
> --
> 2.25.1
>
