On 29.05.2011 22:42, Julian Anastasov wrote:
>
> Fix crash in nf_nat_csum when mangling packets
> in OUTPUT hook where skb->dev is not defined, it is set
> later before POSTROUTING. Problem happens for CHECKSUM_NONE.
> We can check device from rt but using CHECKSUM_PARTIAL
> should be safe (skb_checksum_help).
We don't call helpers in LOCAL_OUT, how can this happen?
>
> Signed-off-by: Julian Anastasov <ja@xxxxxx>
> ---
>
> diff -urp v2.6.39/linux/net/ipv4/netfilter/nf_nat_helper.c linux/net/ipv4/netfilter/nf_nat_helper.c
> --- v2.6.39/linux/net/ipv4/netfilter/nf_nat_helper.c 2011-01-06 00:01:22.000000000 +0200
> +++ linux/net/ipv4/netfilter/nf_nat_helper.c 2011-05-29 23:14:40.166245897 +0300
> @@ -160,7 +160,7 @@ static void nf_nat_csum(struct sk_buff *
>
> if (skb->ip_summed != CHECKSUM_PARTIAL) {
> if (!(rt->rt_flags & RTCF_LOCAL) &&
> - skb->dev->features & NETIF_F_V4_CSUM) {
> + (!skb->dev || skb->dev->features & NETIF_F_V4_CSUM)) {
> skb->ip_summed = CHECKSUM_PARTIAL;
> skb->csum_start = skb_headroom(skb) +
> skb_network_offset(skb) +
>
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