Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759878AbcCDJtR (ORCPT ); Fri, 4 Mar 2016 04:49:17 -0500 Received: from mx2.suse.de ([195.135.220.15]:59728 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758478AbcCDJCw (ORCPT ); Fri, 4 Mar 2016 04:02:52 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Veaceslav Falico , Jay Vosburgh , Andy Gospodarek , "David S . Miller" , Jiri Slaby Subject: [PATCH 3.12 015/116] bonding: fix bond_arp_rcv() race of curr_active_slave Date: Fri, 4 Mar 2016 10:01:00 +0100 Message-Id: X-Mailer: git-send-email 2.7.2 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2428 Lines: 65 From: Veaceslav Falico 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 010d3c3989706d800ae72253773fa6537cc9f74c upstream. bond->curr_active_slave can be changed between its deferences, even to NULL, and thus we might panic. We're always holding the rcu (rx_handler->bond_handle_frame()->bond_arp_rcv()) so fix this by rcu_dereferencing() it and using the saved. Reported-by: Ding Tianhong Fixes: aeea64a ("bonding: don't trust arp requests unless active slave really works") CC: Jay Vosburgh CC: Andy Gospodarek Signed-off-by: Veaceslav Falico Acked-by: Ding Tianhong Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- drivers/net/bonding/bond_main.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index b3892b0d2e61..282d416559dc 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2435,6 +2435,7 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, struct slave *slave) { struct arphdr *arp = (struct arphdr *)skb->data; + struct slave *curr_active_slave; unsigned char *arp_ptr; __be32 sip, tip; int alen; @@ -2479,6 +2480,8 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, bond->params.arp_validate, slave_do_arp_validate(bond, slave), &sip, &tip); + curr_active_slave = rcu_dereference(bond->curr_active_slave); + /* * Backup slaves won't see the ARP reply, but do come through * here for each ARP probe (so we swap the sip/tip to validate @@ -2492,11 +2495,12 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, * is done to avoid endless looping when we can't reach the * arp_ip_target and fool ourselves with our own arp requests. */ + if (bond_is_active_slave(slave)) bond_validate_arp(bond, slave, sip, tip); - else if (bond->curr_active_slave && - time_after(slave_last_rx(bond, bond->curr_active_slave), - bond->curr_active_slave->jiffies)) + else if (curr_active_slave && + time_after(slave_last_rx(bond, curr_active_slave), + curr_active_slave->jiffies)) bond_validate_arp(bond, slave, tip, sip); out_unlock: -- 2.7.2