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

pskb_may_pull() maybe change skb->data and make uh pointer oboslete, so reload uh and guehdr Fixes: 37dd024 ("gue: Receive side for Generic UDP Encapsulation") Cc: Tom Herbert <therbert@google.com> Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
mariux64 · Oct 18, 2014 · d8f00d2 · d8f00d2
1 parent 1245dfc
commit d8f00d2
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
@@ -87,6 +87,9 @@ static int gue_udp_recv(struct sock *sk, struct sk_buff *skb)
 	if (!pskb_may_pull(skb, len))
 		goto drop;
 
+	uh = udp_hdr(skb);
+	guehdr = (struct guehdr *)&uh[1];
+
 	if (guehdr->version != 0)
 		goto drop;