[PATCH net] net: phy: Fix PHY module checks and NULL deref in phy_attach_direct()
From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2017-02-09 03:14:24
Subsystem:
ethernet phy library, networking drivers, the rest · Maintainers:
Andrew Lunn, Heiner Kallweit, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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: cafe8df8b9bc ("net: phy: Fix lack of reference count on PHY driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
David,
This is applicable to the "net" and the "net-next" tree since you
merged "net" into "net-next".
I will fix the PHY driver bind/unbind mess another time, because we are running
out of time for 4.10-rc final, and it's not like it worked before and got
broken in this cycle, it just never worked (the bind/unbind).
Thanks!
drivers/net/phy/phy_device.c | 28 ++++++++++++++++++++--------
1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 0d8f4d3847f6..8c8e15b8739d 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c@@ -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); }
--
2.9.3