[PATCH net] net: ethernet: mediatek: avoid potential invalid memory access

[John Crispin]

On 20/07/17 08:52, sean.wang at mediatek.com wrote:
> From: Sean Wang <sean.wang at mediatek.com>
>
> Potential dangerous invalid memory might be accessed if invalid mac value
> reflected from the forward port field in rxd4 caused by possible potential
> hardware defects. So added a simple sanity checker to avoid the kind of
> situation happening.
>
> Signed-off-by: Sean Wang <sean.wang at mediatek.com>

Thanks, i ran into the same problem last week and was going to send a 
fix shortly.

Acked-by: John Crispin <john at phrozen.org>

> ---
>   drivers/net/ethernet/mediatek/mtk_eth_soc.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index c1dc08c..8175433 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -999,6 +999,12 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
>   		      RX_DMA_FPORT_MASK;
>   		mac--;
>   
> +		if (unlikely(mac < 0 || mac >= MTK_MAC_COUNT ||
> +			     !eth->netdev[mac])) {
> +			netdev->stats.rx_dropped++;
> +			goto release_desc;
> +		}
> +
>   		netdev = eth->netdev[mac];
>   
>   		if (unlikely(test_bit(MTK_RESETTING, &eth->state)))