xfrm: fix xfrm by MARK logic

While using xfrm by MARK feature in
2.6.34 - 2.6.35 kernels, the mark
is always cleared in flowi structure via memset in
_decode_session4 (net/ipv4/xfrm4_policy.c), so
the policy lookup fails.
IPv6 code is affected by this bug too.

Signed-off-by: Peter Kosyh <p.kosyh@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 4a0e77e..6baeabb 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -124,6 +124,8 @@
 	u8 nexthdr = nh[IP6CB(skb)->nhoff];
 
 	memset(fl, 0, sizeof(struct flowi));
+	fl->mark = skb->mark;
+
 	ipv6_addr_copy(&fl->fl6_dst, reverse ? &hdr->saddr : &hdr->daddr);
 	ipv6_addr_copy(&fl->fl6_src, reverse ? &hdr->daddr : &hdr->saddr);