From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH 1/2] bonding: fix netdev event NULL pointer dereference Date: Thu, 11 Apr 2013 17:40:01 +0400 Message-ID: <5166BD31.5020404@cogentembedded.com> References: <1365538644-1502-1-git-send-email-nikolay@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, andy@greyhouse.net, fubar@us.ibm.com, davem@davemloft.net To: Nikolay Aleksandrov Return-path: Received: from mail-lb0-f181.google.com ([209.85.217.181]:50207 "EHLO mail-lb0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935039Ab3DKNlF (ORCPT ); Thu, 11 Apr 2013 09:41:05 -0400 Received: by mail-lb0-f181.google.com with SMTP id r11so1614320lbv.12 for ; Thu, 11 Apr 2013 06:41:03 -0700 (PDT) In-Reply-To: <1365538644-1502-1-git-send-email-nikolay@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: Hello. On 10-04-2013 0:17, Nikolay Aleksandrov wrote: > In commit 471cb5a33dcbd7c529684a2ac7ba4451414ee4a7 ("bonding: remove > usage of dev->master") a bug was introduced which causes a NULL pointer > dereference. If a bond device is in mode 6 (ALB) and a slave is added > it will dereference a NULL pointer in bond_slave_netdev_event(). > This is because in bond_enslave we have bond_alb_init_slave() which > changes the MAC address of the slave and causes a NETDEV_CHANGEADDR. > Then we have in bond_slave_netdev_event(): > struct slave *slave = bond_slave_get_rtnl(slave_dev); > struct bonding *bond = slave->bond; > bond_slave_get_rtnl() dereferences slave_dev->rx_handler_data which at > that time is NULL since netdev_rx_handler_register() is called later. > This is fixed by checking if slave is NULL before dereferencing it. > Signed-off-by: Nikolay Aleksandrov [...] Minor formatting nit. > diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c > index 171b10f..9995ddc 100644 > --- a/drivers/net/bonding/bond_main.c > +++ b/drivers/net/bonding/bond_main.c > @@ -3168,11 +3168,21 @@ static int bond_slave_netdev_event(unsigned long event, > struct net_device *slave_dev) > { > struct slave *slave = bond_slave_get_rtnl(slave_dev); > - struct bonding *bond = slave->bond; > - struct net_device *bond_dev = slave->bond->dev; > + struct bonding *bond; > + struct net_device *bond_dev; > u32 old_speed; > u8 old_duplex; > > + /* > + * A netdev event can be generated while enslaving a device > + * before netdev_rx_handler_register is called in which case > + * slave will be NULL > + */ The preferred multi-line comment style in the networking code is: /* bla * bla */ WBR, Sergei