Fix IPSEC replay window handling

[IPSEC]: Reject packets within replay window but outside the bit mask

Up until this point we've accepted replay window settings greater than
32 but our bit mask can only accomodate 32 packets.  Thus any packet
with a sequence number within the window but outside the bit mask would
be accepted.

This patch causes those packets to be rejected instead.
Signed-off-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/xfrm/xfrm_state.c

@@ -1220,7 +1220,8 @@ int xfrm_replay_check(struct xfrm_state *x, __be32 net_seq)
 		return 0;
 
 	diff = x->replay.seq - seq;
-	if (diff >= x->props.replay_window) {
+	if (diff >= min_t(unsigned int, x->props.replay_window,
+			  sizeof(x->replay.bitmap) * 8)) {
 		x->stats.replay_window++;
 		return -EINVAL;
 	}