Re: [RESEND PATCH] media: mtk-jpeg: Fix use after free bug due to uncanceled work

[AngeloGioacchino Del Regno]

Il 07/03/23 10:27, Zheng Hacker ha scritto:
> Hi,
>
> Is there anyone who can help with this? I can provide more details
> like invoking chain if needed.

Providing more details is always good. Please do.

Meanwhile, adding Irui Wang to the loop: he's doing mtk-jpeg.

Regards,
Angelo

> Thanks,
> Zheng
>
> Zheng Wang <zyytlz.wz@xxxxxxx> 于2023年3月6日周一 14:28写道：
> > 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);
> >          pm_runtime_disable(&pdev->dev);
> >          video_unregister_device(jpeg->vdev);
> >          v4l2_m2m_release(jpeg->m2m_dev);
> > --
> > 2.25.1