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Commit 6d9f66ac authored by Florian Fainelli's avatar Florian Fainelli Committed by David S. Miller
Browse files

net: phy: Fix PHY module checks and NULL deref in phy_attach_direct() 



The Generic PHY drivers gets assigned after we checked that the current
PHY driver is NULL, so we need to check a few things before we can
safely dereference d->driver. This would be causing a NULL deference to
occur when a system binds to the Generic PHY driver. Update
phy_attach_direct() to do the following:

- grab the driver module reference after we have assigned the Generic
  PHY drivers accordingly, and remember we came from the generic PHY
  path

- update the error path to clean up the module reference in case the
  Generic PHY probe function fails

- split the error path involving phy_detacht() to avoid double free/put
  since phy_detach() does all the clean up

- finally, have phy_detach() drop the module reference count before we
  call device_release_driver() for the Generic PHY driver case

Fixes: cafe8df8 ("net: phy: Fix lack of reference count on PHY driver")
Signed-off-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 075ad765

drivers/net/phy/phy_device.c

+20 −8
Original line number Original line Diff line number Diff line
@@ -908,6 +908,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, 
	struct module *ndev_owner = dev->dev.parent->driver->owner;

	struct module *ndev_owner = dev->dev.parent->driver->owner;

	struct mii_bus *bus = phydev->mdio.bus;

	struct mii_bus *bus = phydev->mdio.bus;

	struct device *d = &phydev->mdio.dev;

	struct device *d = &phydev->mdio.dev;

	bool using_genphy = false;

	int err;

	int err;





	/* For Ethernet device drivers that register their own MDIO bus, we

	/* For Ethernet device drivers that register their own MDIO bus, we
@@ -920,11 +921,6 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, 
		return -EIO;

		return -EIO;

	}

	}





	if (!try_module_get(d->driver->owner)) {

		dev_err(&dev->dev, "failed to get the device driver module\n");

		return -EIO;

	}



	get_device(d);

	get_device(d);





	/* Assume that if there is no driver, that it doesn't

	/* Assume that if there is no driver, that it doesn't
@@ -938,12 +934,22 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, 
			d->driver =

			d->driver =

				&genphy_driver[GENPHY_DRV_1G].mdiodrv.driver;

				&genphy_driver[GENPHY_DRV_1G].mdiodrv.driver;





		using_genphy = true;

	}



	if (!try_module_get(d->driver->owner)) {

		dev_err(&dev->dev, "failed to get the device driver module\n");

		err = -EIO;

		goto error_put_device;

	}



	if (using_genphy) {

		err = d->driver->probe(d);

		err = d->driver->probe(d);

		if (err >= 0)

		if (err >= 0)

			err = device_bind_driver(d);

			err = device_bind_driver(d);





		if (err)

		if (err)

			goto error;

			goto error_module_put;

	}

	}





	if (phydev->attached_dev) {

	if (phydev->attached_dev) {
@@ -980,9 +986,14 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, 
	return err;

	return err;





error:

error:

	/* phy_detach() does all of the cleanup below */

	phy_detach(phydev);

	phy_detach(phydev);

	put_device(d);

	return err;



error_module_put:

	module_put(d->driver->owner);

	module_put(d->driver->owner);

error_put_device:

	put_device(d);

	if (ndev_owner != bus->owner)

	if (ndev_owner != bus->owner)

		module_put(bus->owner);

		module_put(bus->owner);

	return err;

	return err;
@@ -1045,6 +1056,8 @@ void phy_detach(struct phy_device *phydev) 




	phy_led_triggers_unregister(phydev);

	phy_led_triggers_unregister(phydev);





	module_put(phydev->mdio.dev.driver->owner);



	/* If the device had no specific driver before (i.e. - it

	/* If the device had no specific driver before (i.e. - it

	 * was using the generic driver), we unbind the device

	 * was using the generic driver), we unbind the device

	 * from the generic driver so that there's a chance a

	 * from the generic driver so that there's a chance a
@@ -1065,7 +1078,6 @@ void phy_detach(struct phy_device *phydev) 
	bus = phydev->mdio.bus;

	bus = phydev->mdio.bus;





	put_device(&phydev->mdio.dev);

	put_device(&phydev->mdio.dev);

	module_put(phydev->mdio.dev.driver->owner);

	if (ndev_owner != bus->owner)

	if (ndev_owner != bus->owner)

		module_put(bus->owner);

		module_put(bus->owner);

}

}