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Message-ID: <538096d2-7b24-e1c7-706d-4d4f952d35eb@baylibre.com>
Date:   Fri, 7 Jul 2023 16:11:32 +0200
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Subject: Re: [RESEND PATCH v2] media: mtk-jpeg: Fix use after free bug due to
 uncanceled work
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To:     Zheng Wang <zyytlz.wz@163.com>, Kyrie.Wu@mediatek.com
Cc:     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
References: <20230707092414.866760-1-zyytlz.wz@163.com>
From:   Alexandre Mergnat <amergnat@baylibre.com>
In-Reply-To: <20230707092414.866760-1-zyytlz.wz@163.com>
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On 07/07/2023 11:24, Zheng Wang 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

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

-- 
Regards,
Alexandre