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References: <20230306062633.200427-1-zyytlz.wz@163.com>
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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Tue, 7 Mar 2023 17:27:41 +0800
Message-ID: <CAJedcCzeVwwi9SkkwouFXUAVhF-tKF4dkqsFqVQwszSwY1SJ0A@mail.gmail.com>
Subject: Re: [RESEND PATCH] media: mtk-jpeg: Fix use after free bug due to
 uncanceled work
To:     Zheng Wang <zyytlz.wz@163.com>
Cc:     mchehab@kernel.org, bin.liu@mediatek.com, matthias.bgg@gmail.com,
        angelogioacchino.delregno@collabora.com,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, 1395428693sheep@gmail.com,
        alex000young@gmail.com
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Hi,

Is there anyone who can help with this? I can provide more details
like invoking chain if needed.

Thanks,
Zheng

Zheng Wang <zyytlz.wz@163.com> =E4=BA=8E2023=E5=B9=B43=E6=9C=886=E6=97=A5=
=E5=91=A8=E4=B8=80 14:28=E5=86=99=E9=81=93=EF=BC=9A
>
> 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@163.com>
> ---
>  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/drive=
rs/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 *p=
dev)
>  static int mtk_jpeg_remove(struct platform_device *pdev)
>  {
>         struct mtk_jpeg_dev *jpeg =3D 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
>