From: Kirill Tkhai <ktkhai@virtuozzo.com>
Date: Fri, 1 Jun 2018 11:30:38 +0000 (+0300)
Subject: kcm: Fix use-after-free caused by clonned sockets
X-Git-Tag: v4.16.15~34
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2a91db8febccf14fa0fc462016d218f8d5093e97;p=linux

kcm: Fix use-after-free caused by clonned sockets

[ Upstream commit eb7f54b90bd8f469834c5e86dcf72ebf9a629811 ]

(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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index dc76bc346829..d3601d421571 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1671,7 +1671,7 @@ static struct file *kcm_clone(struct socket *osock)
 	__module_get(newsock->ops->owner);
 
 	newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
-			 &kcm_proto, true);
+			 &kcm_proto, false);
 	if (!newsk) {
 		sock_release(newsock);
 		return ERR_PTR(-ENOMEM);