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References: <20230707092414.866760-1-zyytlz.wz@163.com>
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From:   Chen-Yu Tsai <wenst@chromium.org>
Date:   Thu, 20 Jul 2023 11:40:01 +0800
Message-ID: <CAGXv+5HjLdZO7mCJyBYk_Kj9SFUJrL3Z4VbxSsPb2qK-mbwkaQ@mail.gmail.com>
Subject: Re: [RESEND PATCH v2] media: mtk-jpeg: Fix use after free bug due to
 uncanceled work
To:     Zheng Wang <zyytlz.wz@163.com>
Cc:     Kyrie.Wu@mediatek.com, bin.liu@mediatek.com, mchehab@kernel.org,
        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, Irui.Wang@mediatek.com,
        security@kernel.org, hackerzheng666@gmail.com,
        1395428693sheep@gmail.com, alex000young@gmail.com
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On Fri, Jul 7, 2023 at 5:25=E2=80=AFPM Zheng Wang <zyytlz.wz@163.com> wrote=
:
>
> 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: Chen-Yu Tsai <wenst@chromium.org>