[IPV6]: Mischecked tw match in __inet6_check_established.

When looking for a conflicting connection the !sk->sk_bound_dev_if
check is performed only for live sockets, but not for timewait-ed.

This is not the case for ipv4, for __inet6_lookup_established in
both ipv4 and ipv6 and for other places that check for tw-s.

Was this missed accidentally? If so, then this patch fixes it and
besides makes use if the dif variable declared in the function.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/inet6_hashtables.c

@@ -193,7 +193,7 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 		   sk2->sk_family	       == PF_INET6	 &&
 		   ipv6_addr_equal(&tw6->tw_v6_daddr, saddr)	 &&
 		   ipv6_addr_equal(&tw6->tw_v6_rcv_saddr, daddr) &&
-		   sk2->sk_bound_dev_if == sk->sk_bound_dev_if) {
+		   (!sk2->sk_bound_dev_if || sk2->sk_bound_dev_if == dif)) {
 			if (twsk_unique(sk, sk2, twp))
 				goto unique;
 			else