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Message-Id: <20190318083716.291164255@linuxfoundation.org>
Date: Mon, 18 Mar 2019 10:24:06 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Xiumei Mu <xmu@...hat.com>,
Xin Long <lucien.xin@...il.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.0 14/43] pptp: dst_release sk_dst_cache in pptp_sock_destruct
5.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Xin Long <lucien.xin@...il.com>
[ Upstream commit 9417d81f4f8adfe20a12dd1fadf73a618cbd945d ]
sk_setup_caps() is called to set sk->sk_dst_cache in pptp_connect,
so we have to dst_release(sk->sk_dst_cache) in pptp_sock_destruct,
otherwise, the dst refcnt will leak.
It can be reproduced by this syz log:
r1 = socket$pptp(0x18, 0x1, 0x2)
bind$pptp(r1, &(0x7f0000000100)={0x18, 0x2, {0x0, @local}}, 0x1e)
connect$pptp(r1, &(0x7f0000000000)={0x18, 0x2, {0x3, @remote}}, 0x1e)
Consecutive dmesg warnings will occur:
unregister_netdevice: waiting for lo to become free. Usage count = 1
v1->v2:
- use rcu_dereference_protected() instead of rcu_dereference_check(),
as suggested by Eric.
Fixes: 00959ade36ac ("PPTP: PPP over IPv4 (Point-to-Point Tunneling Protocol)")
Reported-by: Xiumei Mu <xmu@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/net/ppp/pptp.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -532,6 +532,7 @@ static void pptp_sock_destruct(struct so
pppox_unbind_sock(sk);
}
skb_queue_purge(&sk->sk_receive_queue);
+ dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
}
static int pptp_create(struct net *net, struct socket *sock, int kern)
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