linux-kernel - Re: [RESEND PATCH v2] media: mtk-jpeg: Fix use after free bug due to uncanceled work

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Message-ID: <CAGXv+5HjLdZO7mCJyBYk_Kj9SFUJrL3Z4VbxSsPb2qK-mbwkaQ@mail.gmail.com>
Date:   Thu, 20 Jul 2023 11:40:01 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     Zheng Wang <zyytlz.wz@....com>
Cc:     Kyrie.Wu@...iatek.com, bin.liu@...iatek.com, mchehab@...nel.org,
        matthias.bgg@...il.com, angelogioacchino.delregno@...labora.com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, Irui.Wang@...iatek.com,
        security@...nel.org, hackerzheng666@...il.com,
        1395428693sheep@...il.com, alex000young@...il.com
Subject: Re: [RESEND PATCH v2] media: mtk-jpeg: Fix use after free bug due to
 uncanceled work

On Fri, Jul 7, 2023 at 5:25 PM Zheng Wang <zyytlz.wz@....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@....com>

Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>