[PATCH] act_nat: not all of the ICMP packets need an IP header payload

[Changli Gao <xiaosuo@gmail.com>]

act_nat: not all of the ICMP packets need an IP header payload

not all of the ICMP packets need an IP header payload, so we check the length
of the skbs only when the packets should have an IP header payload.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
----
 net/sched/act_nat.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index 0be49a4..24e614c 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -205,7 +205,7 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
 	{
 		struct icmphdr *icmph;
 
-		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
+		if (!pskb_may_pull(skb, ihl + sizeof(*icmph)))
 			goto drop;
 
 		icmph = (void *)(skb_network_header(skb) + ihl);
@@ -215,6 +215,9 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
 		    (icmph->type != ICMP_PARAMETERPROB))
 			break;
 
+		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
+			goto drop;
+
 		iph = (void *)(icmph + 1);
 		if (egress)
 			addr = iph->daddr;