ipsec: Use the correct ip_local_out function

Because the IPsec output function xfrm_output_resume does its
own dst_output call it should always call __ip_local_output
instead of ip_local_output as the latter may invoke dst_output
directly.  Otherwise the return values from nf_hook and dst_output
may clash as they both use the value 1 but for different purposes.

When that clash occurs this can cause a packet to be used after
it has been freed which usually leads to a crash.  Because the
offending value is only returned from dst_output with qdiscs
such as HTB, this bug is normally not visible.

Thanks to Marco Berizzi for his perseverance in tracking this
down.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/route.c

@@ -160,7 +160,7 @@ static struct dst_ops ipv4_dst_ops = {
 	.negative_advice =	ipv4_negative_advice,
 	.link_failure =		ipv4_link_failure,
 	.update_pmtu =		ip_rt_update_pmtu,
-	.local_out =		ip_local_out,
+	.local_out =		__ip_local_out,
 	.entry_size =		sizeof(struct rtable),
 	.entries =		ATOMIC_INIT(0),
 };

net/ipv6/route.c

@@ -109,7 +109,7 @@ static struct dst_ops ip6_dst_ops_template = {
 	.negative_advice	=	ip6_negative_advice,
 	.link_failure		=	ip6_link_failure,
 	.update_pmtu		=	ip6_rt_update_pmtu,
-	.local_out		=	ip6_local_out,
+	.local_out		=	__ip6_local_out,
 	.entry_size		=	sizeof(struct rt6_info),
 	.entries		=	ATOMIC_INIT(0),
 };