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

[Chen-Yu Tsai]

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

Reviewed-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>