[PATCH 3.11 178/208] ipv6: fix illegal mac_header comparison on 32bit

[Luis Henriques]

3.11.10.3 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <hannes at stressinduktion.org>

Signed-off-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 include/linux/skbuff.h | 5 +++++
 net/ipv6/udp_offload.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 37b4517..e27c8f6 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1643,6 +1643,11 @@ static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
 	skb->mac_header += offset;
 }
 
+static inline void skb_pop_mac_header(struct sk_buff *skb)
+{
+	skb->mac_header = skb->network_header;
+}
+
 static inline void skb_probe_transport_header(struct sk_buff *skb,
 					      const int offset_hint)
 {
diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index 657914b..f21df3f 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -86,7 +86,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
 
 	/* Check if there is enough headroom to insert fragment header. */
 	tnl_hlen = skb_tnl_header_len(skb);
-	if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
+	if (skb_mac_header(skb) < skb->head + tnl_hlen + frag_hdr_sz) {
 		if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
 			goto out;
 	}
-- 
1.8.3.2