[NETFILTER]: Add size check for udp packet mangling.

c5e4af1e · Patrick McHardy · Patrick McHardy · 4125458a · c5e4af1e
Commit c5e4af1e authored Oct 02, 2003 by Patrick McHardy Committed by Patrick McHardy Oct 02, 2003
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net/ipv4/netfilter/ip_nat_helper.c net/ipv4/netfilter/ip_nat_helper.c +6 -0

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--- a/net/ipv4/netfilter/ip_nat_helper.c
+++ b/net/ipv4/netfilter/ip_nat_helper.c
@@ -217,6 +217,12 @@ ip_nat_mangle_udp_packet(struct sk_buff **pskb,
 	struct iphdr *iph;
 	struct udphdr *udph;
+	/* UDP helpers might accidentally mangle the wrong packet */
+	iph = (*pskb)->nh.iph;
+	if ((*pskb)->len < iph->ihl*4 + sizeof(*udph) + 
+	                       match_offset + match_len)
+		return 0;
 	if (!skb_ip_make_writable(pskb, (*pskb)->len))
 		return 0;