Subject: Re: [PATCH net-next-2.6] can: Unify droping of invalid tx skbs and netdev stats

From: Wolfgang Grandegger <[email-masked]>
Date: Mon, 11 Jan 2010 14:00:19 +0100

Hi Oliver,

Oliver Hartkopp wrote:
> To prevent the CAN drivers to operate on invalid socketbuffers the skbs are
> now checked and silently dropped at the xmit-function consistently.
> 
> Also the netdev stats are consistently using the CAN data length code (dlc)
> for [rx|tx]_bytes now.
> 
> Signed-off-by: Oliver Hartkopp <[email-masked]>
> 
> ---
> 
> diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
> index 166cc7e..95567be 100644
> --- a/drivers/net/can/at91_can.c
> +++ b/drivers/net/can/at91_can.c
> @@ -336,18 +336,24 @@ static void at91_chip_stop(struct net_device *dev, enum can_state state)
>   */
>  static netdev_tx_t at91_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  {
>  	struct at91_priv *priv = netdev_priv(dev);
>  	struct net_device_stats *stats = &dev->stats;
>  	struct can_frame *cf = (struct can_frame *)skb->data;
>  	unsigned int mb, prio;
>  	u32 reg_mid, reg_mcr;
>  
> +	if (skb->len != sizeof(*cf) || cf->can_dlc > 8) {
> +		kfree_skb(skb);
> +		dev->stats.tx_dropped++;
> +		return NETDEV_TX_OK;
> +	}

A static inline function "invalid_can_skb(skb)" (or "no_can_skb") would
be handy here:

	if (invalid_can_skb(skb)) {
		kfree_skb(skb);
		dev->stats.tx_dropped++;
		return NETDEV_TX_OK;		
	}

Wolfgang.