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Message-Id: <20170209030526.6029-1-f.fainelli@gmail.com>
Date: Wed, 8 Feb 2017 19:05:26 -0800
From: Florian Fainelli <f.fainelli@...il.com>
To: netdev@...r.kernel.org
Cc: Florian Fainelli <f.fainelli@...il.com>,
maowenan <maowenan@...wei.com>, andrew@...n.ch,
rmk+kernel@...linux.org.uk, festevam@...il.com,
davem@...emloft.net, nikita.yoush@...entembedded.com
Subject: [PATCH net] 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: cafe8df8b9bc ("net: phy: Fix lack of reference count on PHY driver")
Signed-off-by: Florian Fainelli <f.fainelli@...il.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
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