Message-ID: <57c17bfd-83f3-fcce-0eab-e28469fb0ced@collabora.com>
Date:   Tue, 7 Mar 2023 10:49:28 +0100
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Subject: Re: [RESEND PATCH] media: mtk-jpeg: Fix use after free bug due to
 uncanceled work
Content-Language: en-US
To:     Zheng Hacker <hackerzheng666@gmail.com>,
        Zheng Wang <zyytlz.wz@163.com>,
        Irui Wang <irui.wang@mediatek.com>
Cc:     mchehab@kernel.org, bin.liu@mediatek.com, matthias.bgg@gmail.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
References: <20230306062633.200427-1-zyytlz.wz@163.com>
 <CAJedcCzeVwwi9SkkwouFXUAVhF-tKF4dkqsFqVQwszSwY1SJ0A@mail.gmail.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <CAJedcCzeVwwi9SkkwouFXUAVhF-tKF4dkqsFqVQwszSwY1SJ0A@mail.gmail.com>
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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@163.com> 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@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/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
>>