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

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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: cafe8df8b9 ("net: phy: Fix lack of reference count on PHY driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Fainelli 2017-02-08 19:05:26 -08:00 committed by David S. Miller
parent 075ad765ef
commit 6d9f66ac7f
1 changed files with 20 additions and 8 deletions
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28
drivers/net/phy/phy_device.c
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@ -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 mii_bus *bus = phydev->mdio.bus;
struct device *d = &phydev->mdio.dev;
bool using_genphy = false;
int err;
/* 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;
}
if (!try_module_get(d->driver->owner)) {
dev_err(&dev->dev, "failed to get the device driver module\n");
return -EIO;
}
get_device(d);
/* 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 =
&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);
if (err >= 0)
err = device_bind_driver(d);
if (err)
goto error;
goto error_module_put;
}
if (phydev->attached_dev) {
@ -980,9 +986,14 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
return err;
error:
/* phy_detach() does all of the cleanup below */
phy_detach(phydev);
put_device(d);
return err;
error_module_put:
module_put(d->driver->owner);
error_put_device:
put_device(d);
if (ndev_owner != bus->owner)
module_put(bus->owner);
return err;
@ -1045,6 +1056,8 @@ void phy_detach(struct phy_device *phydev)
phy_led_triggers_unregister(phydev);
module_put(phydev->mdio.dev.driver->owner);
/* If the device had no specific driver before (i.e. - it
* was using the generic driver), we unbind the device
* 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;
put_device(&phydev->mdio.dev);
module_put(phydev->mdio.dev.driver->owner);
if (ndev_owner != bus->owner)
module_put(bus->owner);
}