Patch "net: phy: Fix PHY module checks and NULL deref in phy_attach_direct()" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jun 15, 2017

Subsystems (3)

Network drivers Stable branch Ethernet PHY

lore

Share & tools

lore

[email protected]

author maintainer Applied

2017-06-15 10:27 UTC #0 lore raw

This is a note to let you know that I've just added the patch titled

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

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
net-phy-fix-phy-module-checks-and-null-deref-in-phy_attach_direct.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Thu Jun 15 12:25:36 CEST 2017

From: Florian Fainelli <[email protected]>
Date: Wed, 8 Feb 2017 19:05:26 -0800
Subject: net: phy: Fix PHY module checks and NULL deref in phy_attach_direct()

From: Florian Fainelli <[email protected]>

[ Upstream commit 6d9f66ac7fec2a6ccd649e5909806dfe36f1fc25 ]

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 <[email protected]>

Signed-off-by David S. Miller <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 drivers/net/phy/phy_device.c |   29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

drivers/net/phy/phy_device.c +21 -8

@@ -860,6 +860,7 @@ int phy_attach_direct(struct net_device
 	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

@@ -872,11 +873,6 @@ int phy_attach_direct(struct net_device
 		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

@@ -890,12 +886,22 @@ int phy_attach_direct(struct net_device
 			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) {

@@ -931,8 +937,14 @@ int phy_attach_direct(struct net_device
 	return err;
 
 error:
-	put_device(d);
+	/* phy_detach() does all of the cleanup below */
+	phy_detach(phydev);
+	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;

@@ -993,6 +1005,8 @@ void phy_detach(struct phy_device *phyde
 	phydev->attached_dev = NULL;
 	phy_suspend(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

@@ -1013,7 +1027,6 @@ void phy_detach(struct phy_device *phyde
 	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);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/net-phy-fix-lack-of-reference-count-on-phy-driver.patch queue-4.9/net-phy-fix-phy-module-checks-and-null-deref-in-phy_attach_direct.patch