netdev - Re: [PATCH net-next] net: bcmgenet: Add a check for oversized packets

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Date:   Sun, 29 Jan 2023 11:42:36 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     netdev@...r.kernel.org, maxime@...no.tech,
        Doug Berger <opendmb@...il.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] net: bcmgenet: Add a check for oversized packets

On Thu, Jan 26, 2023 at 04:08:19PM -0800, Florian Fainelli wrote:
> Occasionnaly we may get oversized packets from the hardware which
> exceed the nomimal 2KiB buffer size we allocate SKBs with. Add an early
> check which drops the packet to avoid invoking skb_over_panic() and move
> on to processing the next packet.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  drivers/net/ethernet/broadcom/genet/bcmgenet.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> index 21973046b12b..d937daa8ee88 100644
> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> @@ -2316,6 +2316,14 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_rx_ring *ring,
>  			  __func__, p_index, ring->c_index,
>  			  ring->read_ptr, dma_length_status);
>  
> +		if (unlikely(len > RX_BUF_LENGTH)) {
> +			netif_err(priv, rx_status, dev, "oversized packet\n");

I don't think that it is wise move to print to dmesg something that can
be triggered by user over network.

Thanks

> +			dev->stats.rx_length_errors++;
> +			dev->stats.rx_errors++;
> +			dev_kfree_skb_any(skb);
> +			goto next;
> +		}
> +
>  		if (unlikely(!(dma_flag & DMA_EOP) || !(dma_flag & DMA_SOP))) {
>  			netif_err(priv, rx_status, dev,
>  				  "dropping fragmented packet!\n");
> -- 
> 2.25.1
>