ipv6: protect skb->sk accesses from recursive dereference inside the stack

[firefly-linux-kernel-4.4.55.git] / include / net / ip6_route.h

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 1d09b46c1e489325b95f9987327d95ca8affed08..eda131d179d971147f5b7ac254876dbf07946861 100644 (file)
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -174,7 +174,8 @@ int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
 
 static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
 {
-       struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
+       struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
+                               inet6_sk(skb->sk) : NULL;
 
        return (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) ?
               skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));