Subject: Re: [PATCH net v3] net: ravb: Fix possible UAF bug in ravb_remove
To:     Zheng Wang <zyytlz.wz@163.com>
CC:     <davem@davemloft.net>, <linyunsheng@huawei.com>,
        <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:   Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <1a313548-1181-c376-a570-b8efd1d30810@omp.ru>
Date:   Sun, 12 Mar 2023 23:26:41 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.10.1
MIME-Version: 1.0
In-Reply-To: <20230311180630.4011201-1-zyytlz.wz@163.com>
Content-Type: text/plain; charset="utf-8"
Content-Language: en-US
Content-Transfer-Encoding: 7bit
X-KSE-AttachmentFiltering-Interceptor-Info: protection disabled
X-KSE-Antivirus-Interceptor-Info: scan successful
X-KSE-Antivirus-Info: Clean, bases: 3/12/2023 6:17:00 PM
X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 3/11/23 9:06 PM, 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>

   Well, I haven't reviewed v3 yet...

> ---
> 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);
> +	

   Thinking about it again (and looking on some drivers): can ravb_remove() be
called without ravb_close() having been called on the bound devices?
   So I suspect this code should be added to ravb_close()...

[...]

MBR, Sergey