This is a security bug that has been reported to google. It affected all platforms on chrome-os. Please apply this patch to 4.14 4.19 5.4 5.10 and 5.15.

[ Upstream commit c677d7ae83141d390d1253abebafa49c962afb52 ]

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 Signed-off-by: Sasha Levin sashal@kernel.org --- - v2: use cancel_delayed_work_sync instead of cancel_delayed_work suggested by Kyrie. --- drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c index 0051f372a66c..6069ecf420b0 100644 --- a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c +++ b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c @@ -1816,6 +1816,7 @@ 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);