[IPSEC]: Fix reversed ICMP6 policy check

The policy check I added for ICMP on IPv6 is reversed.  This
patch fixes that.

It also adds an skb->sp check so that unprotected packets that
fail the policy check do not crash the machine.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 3c41a6f..c41f3cc4 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -977,7 +977,7 @@
 	struct icmphdr *icmph;
 	struct rtable *rt = (struct rtable *)skb->dst;
 
-	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb) &&
+	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb) && skb->sp &&
 	    skb->sp->xvec[skb->sp->len - 1]->props.flags & XFRM_STATE_ICMP) {
 		int nh;
 
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index c0bea7b..1659d2f 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -644,7 +644,7 @@
 	struct icmp6hdr *hdr;
 	int type;
 
-	if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb) &&
+	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb) && skb->sp &&
 	    skb->sp->xvec[skb->sp->len - 1]->props.flags & XFRM_STATE_ICMP) {
 		int nh;