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Date: Thu, 11 Apr 2013 17:40:01 +0400 From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com> To: Nikolay Aleksandrov <nikolay@...hat.com> CC: netdev@...r.kernel.org, andy@...yhouse.net, fubar@...ibm.com, davem@...emloft.net Subject: Re: [PATCH 1/2] bonding: fix netdev event NULL pointer dereference 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 <nikolay@...hat.com> [...] 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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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