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Date: Fri, 27 Nov 2015 19:34:24 -0800
Message-ID: <CAKh23FkcjtJVrP91x5dBkKZ=nK6anp5dmFmsUm1-58McSQSWbg@mail.gmail.com>
Subject: Re: [PATCH net] drivers: net: xgene: fix possible use after free
From: Iyappan Subramanian <isubramanian@apm.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>, David Miller <davem@davemloft.net>,
        netdev <netdev@vger.kernel.org>, Keyur Chudgar <kchudgar@apm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        ryabinin.a.a@gmail.com,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
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On Wed, Nov 25, 2015 at 9:02 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> Once TX has been enabled on a NIC, it is illegal to access skb,
> as this skb might have been freed by another cpu, from TX completion
> handler.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Mark Rutland <mark.rutland@arm.com>
> Tested-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Iyappan Subramanian <isubramanian@apm.com>
> ---
>  drivers/net/ethernet/apm/xgene/xgene_enet_main.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> index 1adfe7036843..9147a0107c44 100644
> --- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> +++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> @@ -450,12 +450,12 @@ static netdev_tx_t xgene_enet_start_xmit(struct sk_buff *skb,
>                 return NETDEV_TX_OK;
>         }
>
> -       pdata->ring_ops->wr_cmd(tx_ring, count);
>         skb_tx_timestamp(skb);
>
>         pdata->stats.tx_packets++;
>         pdata->stats.tx_bytes += skb->len;
>
> +       pdata->ring_ops->wr_cmd(tx_ring, count);

Thanks Mark and Eric, for the fix.

Acked-by: Iyappan Subramanian <isubramanian@apm.com>

>         return NETDEV_TX_OK;
>  }
>
>
>
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