From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolay Aleksandrov Subject: [PATCH v2 1/4] bonding: fix set mode race conditions Date: Sat, 18 May 2013 13:18:28 +0200 Message-ID: <1368875911-4952-2-git-send-email-nikolay@redhat.com> References: <1368875911-4952-1-git-send-email-nikolay@redhat.com> Cc: fubar@us.ibm.com, andy@greyhouse.net, davem@davemloft.net To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:32873 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754005Ab3ERLV5 (ORCPT ); Sat, 18 May 2013 07:21:57 -0400 In-Reply-To: <1368875911-4952-1-git-send-email-nikolay@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: Changing the mode without any locking can result in multiple races (e.g. upping a bond, enslaving/releasing). Depending on which race is hit the impact can vary from incosistent bond state to kernel crash. Use RTNL to synchronize the mode setting with the dangerous races. Signed-off-by: Nikolay Aleksandrov --- drivers/net/bonding/bond_sysfs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c index ea7a388..77ea237 100644 --- a/drivers/net/bonding/bond_sysfs.c +++ b/drivers/net/bonding/bond_sysfs.c @@ -316,6 +316,9 @@ static ssize_t bonding_store_mode(struct device *d, int new_value, ret = count; struct bonding *bond = to_bond(d); + if (!rtnl_trylock()) + return restart_syscall(); + if (bond->dev->flags & IFF_UP) { pr_err("unable to update mode of %s because interface is up.\n", bond->dev->name); @@ -352,6 +355,7 @@ static ssize_t bonding_store_mode(struct device *d, bond->dev->name, bond_mode_tbl[new_value].modename, new_value); out: + rtnl_unlock(); return ret; } static DEVICE_ATTR(mode, S_IRUGO | S_IWUSR, -- 1.8.1.4