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Date: Fri, 13 Jun 2008 17:11:37 -0700
From: Greg KH <gregkh@suse.de>
To: linux-kernel@vger.kernel.org, stable@kernel.org
Cc: Justin Forbes <jmforbes@linuxtx.org>,
       Zwane Mwaikambo <zwane@arm.linux.org.uk>,
       "Theodore Ts'o" <tytso@mit.edu>, Randy Dunlap <rdunlap@xenotime.net>,
       Dave Jones <davej@redhat.com>, Chuck Wolber <chuckw@quantumlinux.com>,
       Chris Wedgwood <reviews@ml.cw.f00f.org>,
       Michael Krufky <mkrufky@linuxtv.org>, Chuck Ebbert <cebbert@redhat.com>,
       Domenico Andreoli <cavokz@gmail.com>, Willy Tarreau <w@1wt.eu>,
       torvalds@linux-foundation.org, akpm@linux-foundation.org,
       alan@lxorguk.ukuu.org.uk, James Chapman <jchapman@katalix.com>,
       "David S. Miller" <davem@davemloft.net>,
       Chris Wright <chrisw@sous-sol.org>
Subject: [patch 28/47] l2tp: Fix possible WARN_ON from socket code when UDP
	socket is closed
Message-ID: <20080614001137.GB24698@suse.de>
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-stable review patch.  If anyone has any objections, please let us know.

------------------
From: James Chapman <jchapman@katalix.com>

[ upstream commit: 199f7d24ae59894243687a234a909f44a8724506 ]

If an L2TP daemon closes a tunnel socket while packets are queued in
the tunnel's reorder queue, a kernel warning is logged because the
socket is closed while skbs are still referencing it. The fix is to
purge the queue in the socket's release handler.

WARNING: at include/net/sock.h:351 udp_lib_unhash+0x41/0x68()
Pid: 12998, comm: openl2tpd Not tainted 2.6.25 #8
 [<c0423c58>] warn_on_slowpath+0x41/0x51
 [<c05d33a7>] udp_lib_unhash+0x41/0x68
 [<c059424d>] sk_common_release+0x23/0x90
 [<c05d16be>] udp_lib_close+0x8/0xa
 [<c05d8684>] inet_release+0x42/0x48
 [<c0592599>] sock_release+0x14/0x60
 [<c059299f>] sock_close+0x29/0x30
 [<c046ef52>] __fput+0xad/0x15b
 [<c046f1d9>] fput+0x17/0x19
 [<c046c8c4>] filp_close+0x50/0x5a
 [<c046da06>] sys_close+0x69/0x9f
 [<c04048ce>] syscall_call+0x7/0xb

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
 drivers/net/pppol2tp.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/net/pppol2tp.c
+++ b/drivers/net/pppol2tp.c
@@ -1279,6 +1279,7 @@ out:
 static int pppol2tp_release(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
+	struct pppol2tp_session *session;
 	int error;
 
 	if (!sk)
@@ -1296,9 +1297,18 @@ static int pppol2tp_release(struct socke
 	sock_orphan(sk);
 	sock->sk = NULL;
 
+	session = pppol2tp_sock_to_session(sk);
+
 	/* Purge any queued data */
 	skb_queue_purge(&sk->sk_receive_queue);
 	skb_queue_purge(&sk->sk_write_queue);
+	if (session != NULL) {
+		struct sk_buff *skb;
+		while ((skb = skb_dequeue(&session->reorder_q))) {
+			kfree_skb(skb);
+			sock_put(sk);
+		}
+	}
 
 	release_sock(sk);
 

-- 
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