netdev - Re: PROBLEM: pppol2tp over pppoe NULL pointer dereference

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Message-ID: <CAKpUy7Y794CJkAEtbsbTecbPq+KkniSTx4ftCncohzGsuJfk-w@mail.gmail.com>
Date:	Thu, 3 Nov 2011 02:35:41 +0400
From:	Misha Labjuk <spiked.yar@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: PROBLEM: pppol2tp over pppoe NULL pointer dereference

Thanks!!  Panic disappeared.

2011/11/2 Eric Dumazet <eric.dumazet@...il.com>:
> OK thanks, could you try the following patch as well ?
>
> If we release reorder_q.lock, we must not keep a dangling pointer (tmp)
> and restart the whole loop.
>
> 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:
>
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