Re: [PATCH net 2/4] net: ethernet: ti: cpsw: fix device and of_node leaks
From: David Miller
Date: Tue Nov 01 2016 - 12:50:15 EST
From: Johan Hovold <johan@xxxxxxxxxx>
Date: Tue, 1 Nov 2016 17:42:25 +0100
> On Tue, Nov 01, 2016 at 12:27:11PM -0400, David Miller wrote:
>> From: Johan Hovold <johan@xxxxxxxxxx>
>> Date: Tue, 1 Nov 2016 12:03:35 +0100
>> > diff --git a/drivers/net/ethernet/ti/cpsw-phy-sel.c b/drivers/net/ethernet/ti/cpsw-phy-sel.c
>> > index 054a8dd23dae..589beb843f56 100644
>> > --- a/drivers/net/ethernet/ti/cpsw-phy-sel.c
>> > +++ b/drivers/net/ethernet/ti/cpsw-phy-sel.c
>> > @@ -176,8 +176,11 @@ void cpsw_phy_sel(struct device *dev, phy_interface_t phy_mode, int slave)
>> > }
>> > dev = bus_find_device(&platform_bus_type, NULL, node, match);
>> > + of_node_put(node);
>> > priv = dev_get_drvdata(dev);
>> > + put_device(dev);
>> > +
>> > priv->cpsw_phy_sel(priv, phy_mode, slave);
>> > }
>> > EXPORT_SYMBOL_GPL(cpsw_phy_sel);
>> The only reference you have to 'dev' is the one obtained from the
>> bus_find_device() call, therefore you must at least hold onto
>> 'dev' until after the priv->cpsw_phy_sel(priv, phy_mode, slave); call.
> As I mentioned in the commit message "...there is no guarantee that the
> devres-managed struct cpsw_phy_sel_priv will continue to be valid until
> this function returns regardless of this change".
> Specifically, holding a reference to dev does not prevent the
> cpsw_phy_sel driver from being unbound and priv from being freed.
But you should at least hold onto the object while you call a function
pointer embedded in a data structure referred by it.