Re: [PATCH net] drivers: net: xgene: fix possible use after free

[Iyappan Subramanian]

On Wed, Nov 25, 2015 at 9:02 AM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> From: Eric Dumazet <edumazet@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Reported-by: Mark Rutland <mark.rutland@xxxxxxx>
> Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Iyappan Subramanian <isubramanian@xxxxxxx>
> ---
>  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@xxxxxxx>

>         return NETDEV_TX_OK;
>  }
>
>
>
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