bonding: potential null dereference?

Hi,

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;

js

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

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-Jay Vosburgh, IBM Linux Technology Center, [email protected]