mukesh agrawal wrote:
The cause of the crash is that udp_manip_pkt reads *pskb into iph before calling skb_ip_make_writable, and fails to update iph after the call. Since skb_ip_make_writable may delete the original skb when it makes a copy, a page fault may occur when udp_manip_pkt later dereferences iph.
This bug has already been fixed in 2.6.11-rc.
Regards Patrick
diff -uprN linux-2.6.10.orig/net/ipv4/netfilter/ip_nat_proto_udp.c linux-2.6.10.fixed/net/ipv4/netfilter/ip_nat_proto_udp.c
--- linux-2.6.10.orig/net/ipv4/netfilter/ip_nat_proto_udp.c 2004-12-24 16:34:01.000000000 -0500
+++ linux-2.6.10.fixed/net/ipv4/netfilter/ip_nat_proto_udp.c 2005-03-01 19:32:21.000000000 -0500
@@ -95,6 +95,9 @@ udp_manip_pkt(struct sk_buff **pskb,
if (!skb_ip_make_writable(pskb, hdroff + sizeof(hdr))) return 0; + /* skb_ip_make_writable may have copied the skb, and deleted + the original */ + iph = (struct iphdr *)((*pskb)->data + iphdroff);
hdr = (void *)(*pskb)->data + hdroff; if (maniptype == IP_NAT_MANIP_SRC) {
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