[PATCH net] ipv4: Fix traffic triggered IPsec connections.

[Steffen Klassert <steffen.klassert@secunet.com>]

A recent patch removed the dst_free() on the allocated
dst_entry in ipv4_blackhole_route(). The dst_free() marked the
dst_entry as dead and added it to the gc list. I.e. it was setup
for a one time usage. As a result we may now have a blackhole
route cached at a socket on some IPsec scenarios. This makes the
connection unusable.

Fix this by marking the dst_entry directly at allocation time
as 'dead', so it is used only once.

Fixes: b838d5e1c5b6 ("ipv4: mark DST_NOGC and remove the operation of dst_free()")
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/ipv4/route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ac6fde5..3d9f1c2 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2513,7 +2513,7 @@ struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_or
 	struct rtable *ort = (struct rtable *) dst_orig;
 	struct rtable *rt;
 
-	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
+	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_DEAD, 0);
 	if (rt) {
 		struct dst_entry *new = &rt->dst;
 
-- 
2.7.4