Subject: [PATCH] l2tp: fix l2tp_recv_dequeue()

From: Eric Dumazet <[email-masked]>
Date: Wed, 02 Nov 2011 23:53:04 +0100

On 02/11/2011 23:35, Misha Labjuk wrote:

> Thanks!!  Panic disappeared.
> 
>

Thanks !

Here is the official submission then :)

[PATCH] l2tp: fix l2tp_recv_dequeue()

Misha Labjuk reported panics occurring in l2tp_recv_dequeue()

If we release reorder_q.lock, we must not keep a dangling pointer (tmp)
and restart the whole loop.

Reported-by: Misha Labjuk <[email-masked]>
Tested-by: Misha Labjuk <[email-masked]>
Signed-off-by: Eric Dumazet <[email-masked]>
---
 net/l2tp/l2tp_core.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 34b2dde..bf8d50c 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -397,6 +397,7 @@ static void l2tp_recv_dequeue(struct l2tp_session
*session)
 	 * expect to send up next, dequeue it and any other
 	 * in-sequence packets behind it.
 	 */
+start:
 	spin_lock_bh(&session->reorder_q.lock);
 	skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 		if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
@@ -433,7 +434,7 @@ static void l2tp_recv_dequeue(struct l2tp_session
*session)
 		 */
 		spin_unlock_bh(&session->reorder_q.lock);
 		l2tp_recv_dequeue_skb(session, skb);
-		spin_lock_bh(&session->reorder_q.lock);
+		goto start;
 	}

 out: