ipv4: fix a potential use after free in ip_tunnel_core.c

pskb_may_pull() maybe change skb->data and make eth pointer oboslete, so set eth after pskb_may_pull() Fixes:3d7b46cd("ip_tunnel: push generic protocol handling to ip_tunnel module") Cc: Pravin B Shelar <[email protected]> Signed-off-by: Li RongQing <[email protected]> Acked-by: Pravin B Shelar <[email protected]> Signed-off-by: David S. Miller <[email protected]>
needcaffeine · Oct 18, 2014 · 1245dfc · 1245dfc
1 parent f88e671
commit 1245dfc
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
@@ -91,11 +91,12 @@ int iptunnel_pull_header(struct sk_buff *skb, int hdr_len, __be16 inner_proto)
 	skb_pull_rcsum(skb, hdr_len);
 
 	if (inner_proto == htons(ETH_P_TEB)) {
-		struct ethhdr *eh = (struct ethhdr *)skb->data;
+		struct ethhdr *eh;
 
 		if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
 			return -ENOMEM;
 
+		eh = (struct ethhdr *)skb->data;
 		if (likely(ntohs(eh->h_proto) >= ETH_P_802_3_MIN))
 			skb->protocol = eh->h_proto;
 		else