From 938177e9f3e0238c1712210f7bb6def38a5c8d7f Mon Sep 17 00:00:00 2001
From: Simon Horman <horms@verge.net.au>
Date: Thu, 30 May 2013 16:39:29 +0000
Subject: netfilter: Correct calculation using skb->tail and skb-network_header

This corrects an regression introduced by "net: Use 16bits for *_headers
fields of struct skbuff" when NET_SKBUFF_DATA_USES_OFFSET is not set. In
that case skb->tail will be a pointer whereas skb->network_header
will be an offset from head. This is corrected by using wrappers that
ensure that calculations are always made using pointers.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netfilter/nf_nat_helper.c b/net/netfilter/nf_nat_helper.c
index 5fea563..85e20a9 100644
--- a/net/netfilter/nf_nat_helper.c
+++ b/net/netfilter/nf_nat_helper.c
@@ -104,7 +104,7 @@ static void mangle_contents(struct sk_buff *skb,
 	/* move post-replacement */
 	memmove(data + match_offset + rep_len,
 		data + match_offset + match_len,
-		skb->tail - (skb->network_header + dataoff +
+		skb_tail_pointer(skb) - (skb_network_header(skb) + dataoff +
 			     match_offset + match_len));
 
 	/* insert data from buffer */
-- 
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