2.6.32.49.17.ipv6-udp-fix-the-wrong-headroom-check.patch

From a9cf73ea7ff78f52662c8658d93c226effbbedde Mon Sep 17 00:00:00 2001
From: Shan Wei <shanwei@cn.fujitsu.com>
Date: Tue, 19 Apr 2011 22:52:49 +0000
Subject: ipv6: udp: fix the wrong headroom check

From: Shan Wei <shanwei@cn.fujitsu.com>

commit a9cf73ea7ff78f52662c8658d93c226effbbedde upstream.

At this point, skb->data points to skb_transport_header.
So, headroom check is wrong.

For some case:bridge(UFO is on) + eth device(UFO is off),
there is no enough headroom for IPv6 frag head.
But headroom check is always false.

This will bring about data be moved to there prior to skb->head,
when adding IPv6 frag header to skb.

Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/ipv6/udp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1141,7 +1141,7 @@ static struct sk_buff *udp6_ufo_fragment
 	skb->ip_summed = CHECKSUM_NONE;
 
 	/* Check if there is enough headroom to insert fragment header. */
-	if ((skb_headroom(skb) < frag_hdr_sz) &&
+	if ((skb_mac_header(skb) < skb->head + frag_hdr_sz) &&
 	    pskb_expand_head(skb, frag_hdr_sz, 0, GFP_ATOMIC))
 		goto out;