Subject: Re: [PATCH net v3] net: ravb: Fix possible UAF bug in ravb_remove
To:     Zheng Wang <zyytlz.wz@163.com>, <s.shtylyov@omp.ru>
CC:     <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
        <pabeni@redhat.com>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <hackerzheng666@gmail.com>,
        <1395428693sheep@gmail.com>, <alex000young@gmail.com>
References: <20230311180630.4011201-1-zyytlz.wz@163.com>
From:   Yunsheng Lin <linyunsheng@huawei.com>
Message-ID: <57f6d87e-8bfb-40fc-7724-89676c2e75ef@huawei.com>
Date:   Mon, 13 Mar 2023 09:15:45 +0800
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On 2023/3/12 2:06, Zheng Wang wrote:
> In ravb_probe, priv->work was bound with ravb_tx_timeout_work.
> If timeout occurs, it will start the work. And if we call
> ravb_remove without finishing the work, there may be a
> use-after-free bug on ndev.
> 
> Fix it by finishing the job before cleanup in ravb_remove.
> 
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> ---
> v3:
> - fix typo in commit message
> v2:
> - stop dev_watchdog so that handle no more timeout work suggested by Yunsheng Lin,
> add an empty line to make code clear suggested by Sergey Shtylyov
> ---
>  drivers/net/ethernet/renesas/ravb_main.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 0f54849a3823..eb63ea788e19 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -2892,6 +2892,10 @@ static int ravb_remove(struct platform_device *pdev)
>  	struct ravb_private *priv = netdev_priv(ndev);
>  	const struct ravb_hw_info *info = priv->info;
>  
> +	netif_carrier_off(ndev);
> +	netif_tx_disable(ndev);
> +	cancel_work_sync(&priv->work);

LGTM.
Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>

As noted by Sergey, ravb_remove() and ravb_close() may
share the same handling, but may require some refactoring
in order to do that. So for a fix, it seems the easiest
way to just add the handling here.

> +	
>  	/* Stop PTP Clock driver */
>  	if (info->ccc_gac)
>  		ravb_ptp_stop(ndev);
>