From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: PROBLEM: pppol2tp over pppoe NULL pointer dereference Date: Wed, 02 Nov 2011 08:07:32 +0100 Message-ID: <1320217652.30178.1.camel@edumazet-laptop> References: <1320186916.4728.1.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org To: Misha Labjuk Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:35593 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750813Ab1KBHHi (ORCPT ); Wed, 2 Nov 2011 03:07:38 -0400 Received: by wyh15 with SMTP id 15so1145152wyh.19 for ; Wed, 02 Nov 2011 00:07:37 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Le mercredi 02 novembre 2011 =C3=A0 09:04 +0400, Misha Labjuk a =C3=A9c= rit : > 2011/11/2 Eric Dumazet : > > > > On what kind of NIC this is happening ? > > >=20 > Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit > Ethernet controller (rev 02) > Kernel driver in use: r8169 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; } =20 out: