From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753986Ab0AXQXT (ORCPT ); Sun, 24 Jan 2010 11:23:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753724Ab0AXQXQ (ORCPT ); Sun, 24 Jan 2010 11:23:16 -0500 Received: from mail-px0-f182.google.com ([209.85.216.182]:39487 "EHLO mail-px0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753505Ab0AXQXP (ORCPT ); Sun, 24 Jan 2010 11:23:15 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:content-transfer-encoding :in-reply-to:user-agent; b=g/MCJp5b5XSjnfl6vpXXGHPBXCgMYGNjFmrduSggM6r37g9UQXzPO3CZjR4s8K4JxL 18UZY0rSnWfvMNfyDGVVDLMrvvBKkGh0z6sNHTPZ1Rka8Rn9CwyV1OpUQDHQZwTGAfTC cqyyc+Q3JDKtZXk1dvtRN6jUsXul/qgF6AatY= Date: Mon, 25 Jan 2010 00:25:23 +0800 From: =?utf-8?Q?Am=C3=A9rico?= Wang To: Bruno =?utf-8?Q?Pr=C3=A9mont?= Cc: Eric Dumazet , "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [2.6.33-rc5 regression] NULL pointer dereference in vlan_skb_recv - probably introduced by commit 9793241fe92f7d9303fb221e43fc598eb065f267 Message-ID: <20100124162523.GC11037@hack> References: <20100123165657.187c11e4@neptune.home> <20100123223132.0e62d8cb@neptune.home> <4B5C4E5E.2010507@gmail.com> <20100124160228.366f4e72@neptune.home> <20100124162549.2b39b222@neptune.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20100124162549.2b39b222@neptune.home> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 24, 2010 at 04:25:49PM +0100, Bruno Prémont wrote: >On Sun, 24 January 2010 Eric Dumazet wrote: >> Le 23/01/2010 22:31, Bruno Prémont a écrit : >> >> Above part of code did change between 2.6.32 and 2.6.33-rc5 with >> >> commit 9793241fe92f7d9303fb221e43fc598eb065f267 (vlan: Precise RX >> >> stats accounting) >> >> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=9793241fe92f7d9303fb221e43fc598eb065f267 >> > >> > Reverting just that commit gets the system running correctly. >> > >> > Bruno >> >> I have no idea how this patch can break vlan networking. >> >> Your disassembly and .config seems to show your machine is not SMP > >Exact > >> Maybe something is broken on UP and alloc_percpu() ? > >Apparently not, see below and previous mail > >> Could you add a debug in vlan_dev_init() > >In addition to previous mail, I'm also dumping the result of >vlan_dev_info(dev) shows that the returned pointer is not the same >during vlan_dev_init() and vlan_skb_recv() ... > >diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c >index b788978..f370ce1 100644 >--- a/net/8021q/vlan_dev.c >+++ b/net/8021q/vlan_dev.c >@@ -165,8 +165,11 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev, > > rx_stats = per_cpu_ptr(vlan_dev_info(dev)->vlan_rx_stats, > smp_processor_id()); I am thinking if vlan_dev_info(dev) here should be vlan_dev_info(skb->dev)... >- rx_stats->rx_packets++; >- rx_stats->rx_bytes += skb->len; >+ if (rx_stats) { >+ rx_stats->rx_packets++; >+ rx_stats->rx_bytes += skb->len; >+ } else >+ pr_err("vlan_skb_recv() %p->rx_stats=%p -> %p\n", vlan_dev_info(dev), vlan_dev_info(dev)->vlan_rx_stats, rx_stats); > > skb_pull_rcsum(skb, VLAN_HLEN); > >@@ -738,6 +741,7 @@ static int vlan_dev_init(struct net_device *dev) > vlan_dev_info(dev)->vlan_rx_stats = alloc_percpu(struct vlan_rx_stats); > if (!vlan_dev_info(dev)->vlan_rx_stats) > return -ENOMEM; >+ pr_err("vlan_dev_init() %p->rx_stats=%p\n", vlan_dev_info(dev), vlan_dev_info(dev)->vlan_rx_stats); > > return 0; > } > >This slightly adjusted change produces the following output: >... >[ 1192.257978] ADDRCONF(NETDEV_UP): lan: link is not ready >[ 1192.399059] 802.1Q VLAN Support v1.8 Ben Greear >[ 1192.399063] All bugs added by David S. Miller >[ 1192.404475] vlan_dev_init() da4ff360->rx_stats=dbd5a340 > ^^^^^^^^ >[ 1196.000225] b44: lan: Link is up at 100 Mbps, full duplex. >[ 1196.000234] b44: lan: Flow control is off for TX and off for RX. >[ 1196.000379] ADDRCONF(NETDEV_CHANGE): lan: link becomes ready >[ 1203.160226] lan.658: no IPv6 routers present >[ 1212.760561] vlan_skb_recv() ddbb8b60->rx_stats=(null) -> (null) > ^^^^^^^^ >[ 1212.794961] vlan_skb_recv() ddbb8b60->rx_stats=(null) -> (null) >[ 1219.247018] svc: failed to register lockdv1 RPC service (errno 97). >[ 1219.249919] mount.nfs used greatest stack depth: 1008 bytes left >[ 1221.388602] vlan_skb_recv() ddbb8b60->rx_stats=(null) -> (null) >[ 1221.388690] vlan_skb_recv() ddbb8b60->rx_stats=(null) -> (null) >[ 1278.793350] vlan_skb_recv() ddbb8b60->rx_stats=(null) -> (null) >[ 1283.750363] vlan_skb_recv() ddbb8b60->rx_stats=(null) -> (null) >... > >This might explain the NULL rx_stats pointer, but why do there exist >two distinct vlan_dev_info(dev)? (unless in one case dev would be >the physical network device and in the other case it would be vlan device? >that is lan versus lan.658 in my case...) > >Thanks, >Bruno >-- >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html >Please read the FAQ at http://www.tux.org/lkml/ -- Live like a child, think like the god.