media: mtk-jpeg: Fix use after free bug due to uncanceled work

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
Fixes: b2f0d2724ba4 ("[media] vcodec: mediatek: Add Mediatek JPEG Decoder Driver")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

diff --git a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
index 40cb3cb87ba17def35144f51729a64bb59b56e13..621038aab11689865a1bb80b7e723e1569606378 100644 (file)
--- a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
+++ b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
@@ -1403,6 +1403,7 @@ static void mtk_jpeg_remove(struct platform_device *pdev)
 {
        struct mtk_jpeg_dev *jpeg = platform_get_drvdata(pdev);
 
+       cancel_delayed_work_sync(&jpeg->job_timeout_work);
        pm_runtime_disable(&pdev->dev);
        video_unregister_device(jpeg->vdev);
        v4l2_m2m_release(jpeg->m2m_dev);