netdev - Re: [PATCH net] sfc: fix potential memleak in __ef100_hard_start

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Date:   Thu, 17 Nov 2022 20:41:52 +0800
From:   Zhang Changzhong <zhangchangzhong@...wei.com>
To:     Leon Romanovsky <leon@...nel.org>
CC:     Edward Cree <ecree.xilinx@...il.com>,
        Martin Habets <habetsm.xilinx@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        "Eric Dumazet" <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] sfc: fix potential memleak in
 __ef100_hard_start_xmit()



On 2022/11/17 19:36, Leon Romanovsky wrote:
> On Thu, Nov 17, 2022 at 03:50:09PM +0800, Zhang Changzhong wrote:
>> The __ef100_hard_start_xmit() returns NETDEV_TX_OK without freeing skb
>> in error handling case, add dev_kfree_skb_any() to fix it.
>>
>> Fixes: 51b35a454efd ("sfc: skeleton EF100 PF driver")
>> Signed-off-by: Zhang Changzhong <zhangchangzhong@...wei.com>
>> ---
>>  drivers/net/ethernet/sfc/ef100_netdev.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/net/ethernet/sfc/ef100_netdev.c b/drivers/net/ethernet/sfc/ef100_netdev.c
>> index 88fa295..ddcc325 100644
>> --- a/drivers/net/ethernet/sfc/ef100_netdev.c
>> +++ b/drivers/net/ethernet/sfc/ef100_netdev.c
>> @@ -218,6 +218,7 @@ netdev_tx_t __ef100_hard_start_xmit(struct sk_buff *skb,
>>  		   skb->len, skb->data_len, channel->channel);
>>  	if (!efx->n_channels || !efx->n_tx_channels || !channel) {
>>  		netif_stop_queue(net_dev);
>> +		dev_kfree_skb_any(skb);
>>  		goto err;
>>  	}
> 
> ef100 doesn't release in __ef100_enqueue_skb() either. SKB shouldn't be
> NULL or ERR at this stage.

SKB shouldn't be NULL or ERR, so it can be freed. But this code looks weird.

> 
> diff --git a/drivers/net/ethernet/sfc/ef100_tx.c b/drivers/net/ethernet/sfc/ef100_tx.c
> index 29ffaf35559d..426706b91d02 100644
> --- a/drivers/net/ethernet/sfc/ef100_tx.c
> +++ b/drivers/net/ethernet/sfc/ef100_tx.c
> @@ -497,7 +497,7 @@ int __ef100_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
> 
>  err:
>         efx_enqueue_unwind(tx_queue, old_insert_count);
> -       if (!IS_ERR_OR_NULL(skb))
> +       if (rc)
>                 dev_kfree_skb_any(skb);
> 
>         /* If we're not expecting another transmit and we had something to push
> 
> 
>>  
>> -- 
>> 2.9.5
>>
> .
>