[IPV6]: Fix slab corruption running ip6sic

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

net/ipv6/xfrm6_tunnel.c

@@ -407,7 +407,7 @@ static int xfrm6_tunnel_rcv(struct sk_buff **pskb)
 		return 0;
 
 	spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&iph->saddr);
-	return xfrm6_rcv_spi(pskb, spi);
+	return xfrm6_rcv_spi(pskb, spi) > 0 ? : 0;
 }
 
 static void xfrm6_tunnel_err(struct sk_buff *skb, struct inet6_skb_parm *opt,