[patch 28/47] l2tp: Fix possible WARN_ON from socket code when UDP socket is closed

Greg KH
2008-06-14T00:21:43Z

[-- Attachment #1: l2tp-fix-possible-warn_on-from-socket-code-when-udp-socket-is-closed.patch --]
[-- Type: text/plain, Size: 1904 bytes --]

-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);

--