[PATCH 4.14 004/165] xfrm: free skb if nlsk pointer is NULL

[Greg Kroah-Hartman]

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

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

From: Florian Westphal <fw@xxxxxxxxx>

[ Upstream commit 86126b77dcd551ce223e7293bb55854e3df05646 ]

nlmsg_multicast() always frees the skb, so in case we cannot call
it we must do that ourselves.

Fixes: 21ee543edc0dea ("xfrm: fix race between netns cleanup and state expire notification")
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/xfrm/xfrm_user.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1021,10 +1021,12 @@ static inline int xfrm_nlmsg_multicast(s
 {
 	struct sock *nlsk = rcu_dereference(net->xfrm.nlsk);
 
-	if (nlsk)
-		return nlmsg_multicast(nlsk, skb, pid, group, GFP_ATOMIC);
-	else
-		return -1;
+	if (!nlsk) {
+		kfree_skb(skb);
+		return -EPIPE;
+	}
+
+	return nlmsg_multicast(nlsk, skb, pid, group, GFP_ATOMIC);
 }
 
 static inline size_t xfrm_spdinfo_msgsize(void)