ipv6: fix a potential use after free in ip6_offload.c

pskb_may_pull() maybe change skb->data and make opth pointer oboslete,
so set the opth again

Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 9034f76..91014d3 100644 (file)
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -46,6 +46,7 @@ static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
                if (unlikely(!pskb_may_pull(skb, len)))
                        break;
 
+               opth = (void *)skb->data;
                proto = opth->nexthdr;
                __skb_pull(skb, len);
        }