[PATCH] media: verisilicon: fix use after free bug in hantro_remove due to race condition

[Ezequiel Garcia]

Hi Ma,

This was already discussed:

https://patchwork.kernel.org/project/linux-media/patch/20230313154132.3684181-1-zyytlz.wz@163.com/

Thanks,
Ezequiel

On Fri, Sep 15, 2023 at 8:51 AM Ma Ke <make_ruc2021 at 163.com> wrote:
>
> In hantro_probe, vpu->watchdog_work is bound with hantro_watchdog function. In
> hantro_end_prepare_run, it will started by schedule_delayed_work. If there is an
> unfinished work in hantro_remove, there may be a race condition and trigger UAF
> bug.
>
> Signed-off-by: Ma Ke <make_ruc2021 at 163.com>
> ---
>  drivers/media/platform/verisilicon/hantro_drv.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c
> index 423fc85d79ee..1a5b3a85c520 100644
> --- a/drivers/media/platform/verisilicon/hantro_drv.c
> +++ b/drivers/media/platform/verisilicon/hantro_drv.c
> @@ -1187,6 +1187,7 @@ static void hantro_remove(struct platform_device *pdev)
>
>         v4l2_info(&vpu->v4l2_dev, "Removing %s\n", pdev->name);
>
> +       cancel_delayed_work_sync(&vpu->watchdog_work);
>         media_device_unregister(&vpu->mdev);
>         hantro_remove_dec_func(vpu);
>         hantro_remove_enc_func(vpu);
> --
> 2.37.2
>