[PATCH 3.15 02/26] xfrm: Fix refcount imbalance in xfrm_lookup

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Steffen Klassert <steffen.klassert@secunet.com>

[ Upstream commit b7eea4545ea775df957460f58eb56085a8892856 ]

xfrm_lookup must return a dst_entry with a refcount for the caller.
Git commit 1a1ccc96abb ("xfrm: Remove caching of xfrm_policy_sk_bundles")
removed this refcount for the socket policy case accidentally.
This patch restores it and sets DST_NOCACHE flag to make sure
that the dst_entry is freed when the refcount becomes null.

Fixes: 1a1ccc96abb ("xfrm: Remove caching of xfrm_policy_sk_bundles")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/xfrm/xfrm_policy.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2107,6 +2107,8 @@ struct dst_entry *xfrm_lookup(struct net
 				goto no_transform;
 			}
 
+			dst_hold(&xdst->u.dst);
+			xdst->u.dst.flags |= DST_NOCACHE;
 			route = xdst->route;
 		}
 	}