From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932768Ab0C3X13 (ORCPT ); Tue, 30 Mar 2010 19:27:29 -0400 Received: from kroah.org ([198.145.64.141]:46816 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932693Ab0C3XWF (ORCPT ); Tue, 30 Mar 2010 19:22:05 -0400 X-Mailbox-Line: From linux@linux.site Tue Mar 30 15:48:53 2010 Message-Id: <20100330224852.835762887@linux.site> User-Agent: quilt/0.47-14.9 Date: Tue, 30 Mar 2010 15:42:56 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Eric Dumazet , "David S. Miller" , Greg Kroah-Hartman Subject: [142/156] net: Potential null skb->dev dereference In-Reply-To: <20100330230630.GA28824@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Eric Dumazet [ Upstream commit 0641e4fbf2f824faee00ea74c459a088d94905fd ] When doing "ifenslave -d bond0 eth0", there is chance to get NULL dereference in netif_receive_skb(), because dev->master suddenly becomes NULL after we tested it. We should use ACCESS_ONCE() to avoid this (or rcu_dereference()) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/netdevice.h | 8 ++++---- net/8021q/vlan_core.c | 4 ++-- net/core/dev.c | 8 +++++--- 3 files changed, 11 insertions(+), 9 deletions(-) --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2023,12 +2023,12 @@ static inline void skb_bond_set_mac_by_m * duplicates except for 802.3ad ETH_P_SLOW, alb non-mcast/bcast, and * ARP on active-backup slaves with arp_validate enabled. */ -static inline int skb_bond_should_drop(struct sk_buff *skb) +static inline int skb_bond_should_drop(struct sk_buff *skb, + struct net_device *master) { - struct net_device *dev = skb->dev; - struct net_device *master = dev->master; - if (master) { + struct net_device *dev = skb->dev; + if (master->priv_flags & IFF_MASTER_ARPMON) dev->last_rx = jiffies; --- a/net/8021q/vlan_core.c +++ b/net/8021q/vlan_core.c @@ -11,7 +11,7 @@ int __vlan_hwaccel_rx(struct sk_buff *sk if (netpoll_rx(skb)) return NET_RX_DROP; - if (skb_bond_should_drop(skb)) + if (skb_bond_should_drop(skb, ACCESS_ONCE(skb->dev->master))) goto drop; __vlan_hwaccel_put_tag(skb, vlan_tci); @@ -82,7 +82,7 @@ vlan_gro_common(struct napi_struct *napi { struct sk_buff *p; - if (skb_bond_should_drop(skb)) + if (skb_bond_should_drop(skb, ACCESS_ONCE(skb->dev->master))) goto drop; __vlan_hwaccel_put_tag(skb, vlan_tci); --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2421,6 +2421,7 @@ int netif_receive_skb(struct sk_buff *sk { struct packet_type *ptype, *pt_prev; struct net_device *orig_dev; + struct net_device *master; struct net_device *null_or_orig; int ret = NET_RX_DROP; __be16 type; @@ -2440,11 +2441,12 @@ int netif_receive_skb(struct sk_buff *sk null_or_orig = NULL; orig_dev = skb->dev; - if (orig_dev->master) { - if (skb_bond_should_drop(skb)) + master = ACCESS_ONCE(orig_dev->master); + if (master) { + if (skb_bond_should_drop(skb, master)) null_or_orig = orig_dev; /* deliver only exact match */ else - skb->dev = orig_dev->master; + skb->dev = master; } __get_cpu_var(netdev_rx_stat).total++;