From: Kirill Tkhai <ktkhai@virtuozzo.com>
Date: Fri, 1 Jun 2018 14:30:38 +0300
Subject: kcm: Fix use-after-free caused by clonned sockets
Git-commit: eb7f54b90bd8f469834c5e86dcf72ebf9a629811
Patch-mainline: v4.17
References: networking-stable-18_06_08

(resend for properly queueing in patchwork)

kcm_clone() creates kernel socket, which does not take net counter.
Thus, the net may die before the socket is completely destructed,
i.e. kcm_exit_net() is executed before kcm_done().

Reported-by: syzbot+5f1a04e374a635efc426@syzkaller.appspotmail.com
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/kcm/kcmsock.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1667,7 +1667,7 @@ static int kcm_clone(struct socket *osoc
 	}
 
 	newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
-			 &kcm_proto, true);
+			 &kcm_proto, false);
 	if (!newsk) {
 		err = -ENOMEM;
 		goto out_sk_alloc_fail;