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Message-ID: <16196.1262972760@death.nxdomain.ibm.com>
Date: Fri, 08 Jan 2010 09:46:00 -0800
From: Jay Vosburgh <fubar@...ibm.com>
To: Jiri Slaby <jirislaby@...il.com>
cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
bonding-devel@...ts.sourceforge.net,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: bonding: potential null dereference?
Jiri Slaby <jirislaby@...il.com> wrote:
>I'm looking at Stanse errors and it detected a suspected behaviour in
>bonding. In bond_slave_netdev_event, bond_dev is passed down to
>netdev_priv, but due to 'if (bond_dev)' test later, it deduced it can be
>also NULL.
>
>I can see, that passing NULL to netdev_priv is OK nowadays, as it just
>returns NULL + some offset. But what if this changes in the future?
>
>I would bake a patch, but I don't know if bond_dev may be NULL at all
>(i.e. superfluous test) or may not (wrong netdev_priv(bond_dev)).
>
>static int (unsigned long event,
> struct net_device *slave_dev)
>{
> struct net_device *bond_dev = slave_dev->master;
> struct bonding *bond = netdev_priv(bond_dev);
>
> switch (event) {
> case NETDEV_UNREGISTER:
> if (bond_dev) {
> if (bond->setup_by_slave)
> bond_release_and_destroy(bond_dev,
>slave_dev);
> else
> bond_release(bond_dev, slave_dev);
> }
> break;
I don't believe bond_dev will ever actually be NULL here,
because bond_netdev_event (the only caller of bond_slave_netdev_event)
checks that the device is, in fact, a bonding slave before the call.
Just from looking at the code, I don't see any issues with
removing the "if (bond_dev)" test.
-J
---
-Jay Vosburgh, IBM Linux Technology Center, fubar@...ibm.com
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