From: Julian Anastasov Date: Sun, 29 May 2011 20:42:29 +0000 (+0300) Subject: netfilter: nf_nat: fix crash in nf_nat_csum X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d9be76f38526dccf84062e3ac3ed3a6a97698565;p=linux-beck.git netfilter: nf_nat: fix crash in nf_nat_csum 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). Signed-off-by: Julian Anastasov Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c index 99cfa28b6d38..ebc5f8894f99 100644 --- a/net/ipv4/netfilter/nf_nat_helper.c +++ b/net/ipv4/netfilter/nf_nat_helper.c @@ -160,7 +160,7 @@ static void nf_nat_csum(struct sk_buff *skb, const struct iphdr *iph, void *data 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) +