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

[Irui Wang (王瑞)]

Dear Angelo and Zheng,

Thanks for your patch and comments.

Dear Kyrie,

Please help to check this, thanks.

Best Regards

On Tue, 2023-03-07 at 10:49 +0100, AngeloGioacchino Del Regno wrote:
> 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
> > > 
> 
> 
>