From 7749ae610a243758b5c51b2d6c314cb404a6241e Mon Sep 17 00:00:00 2001
From: Florian Fainelli <f.fainelli@gmail.com>
Date: Fri, 17 Feb 2017 16:07:34 -0800
Subject: net: phy: Check phydev->drv

There are number of function calls, originating from user-space,
typically through the Ethernet driver that can make us crash by
dereferencing phydev->drv which will be NULL once we unbind the driver
from the PHY.

There are still functional issues that prevent an unbind then rebind to
work, but these will be addressed separately.

Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index a9be26f..4ce0fac 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -541,7 +541,7 @@ int phy_mii_ioctl(struct phy_device *phydev, struct ifreq *ifr, int cmd)
 		return 0;
 
 	case SIOCSHWTSTAMP:
-		if (phydev->drv->hwtstamp)
+		if (phydev->drv && phydev->drv->hwtstamp)
 			return phydev->drv->hwtstamp(phydev, ifr);
 		/* fall through */
 
@@ -566,6 +566,9 @@ static int phy_start_aneg_priv(struct phy_device *phydev, bool sync)
 	bool trigger = 0;
 	int err;
 
+	if (!phydev->drv)
+		return -EIO;
+
 	mutex_lock(&phydev->lock);
 
 	if (AUTONEG_DISABLE == phydev->autoneg)
@@ -965,7 +968,7 @@ void phy_state_machine(struct work_struct *work)
 
 	old_state = phydev->state;
 
-	if (phydev->drv->link_change_notify)
+	if (phydev->drv && phydev->drv->link_change_notify)
 		phydev->drv->link_change_notify(phydev);
 
 	switch (phydev->state) {
@@ -1258,6 +1261,9 @@ EXPORT_SYMBOL(phy_write_mmd_indirect);
  */
 int phy_init_eee(struct phy_device *phydev, bool clk_stop_enable)
 {
+	if (!phydev->drv)
+		return -EIO;
+
 	/* According to 802.3az,the EEE is supported only in full duplex-mode.
 	 * Also EEE feature is active when core is operating with MII, GMII
 	 * or RGMII (all kinds). Internal PHYs are also allowed to proceed and
@@ -1335,6 +1341,9 @@ EXPORT_SYMBOL(phy_init_eee);
  */
 int phy_get_eee_err(struct phy_device *phydev)
 {
+	if (!phydev->drv)
+		return -EIO;
+
 	return phy_read_mmd_indirect(phydev, MDIO_PCS_EEE_WK_ERR, MDIO_MMD_PCS);
 }
 EXPORT_SYMBOL(phy_get_eee_err);
@@ -1351,6 +1360,9 @@ int phy_ethtool_get_eee(struct phy_device *phydev, struct ethtool_eee *data)
 {
 	int val;
 
+	if (!phydev->drv)
+		return -EIO;
+
 	/* Get Supported EEE */
 	val = phy_read_mmd_indirect(phydev, MDIO_PCS_EEE_ABLE, MDIO_MMD_PCS);
 	if (val < 0)
@@ -1384,6 +1396,9 @@ int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
 {
 	int val = ethtool_adv_to_mmd_eee_adv_t(data->advertised);
 
+	if (!phydev->drv)
+		return -EIO;
+
 	phy_write_mmd_indirect(phydev, MDIO_AN_EEE_ADV, MDIO_MMD_AN, val);
 
 	return 0;
@@ -1392,7 +1407,7 @@ EXPORT_SYMBOL(phy_ethtool_set_eee);
 
 int phy_ethtool_set_wol(struct phy_device *phydev, struct ethtool_wolinfo *wol)
 {
-	if (phydev->drv->set_wol)
+	if (phydev->drv && phydev->drv->set_wol)
 		return phydev->drv->set_wol(phydev, wol);
 
 	return -EOPNOTSUPP;
@@ -1401,7 +1416,7 @@ EXPORT_SYMBOL(phy_ethtool_set_wol);
 
 void phy_ethtool_get_wol(struct phy_device *phydev, struct ethtool_wolinfo *wol)
 {
-	if (phydev->drv->get_wol)
+	if (phydev->drv && phydev->drv->get_wol)
 		phydev->drv->get_wol(phydev, wol);
 }
 EXPORT_SYMBOL(phy_ethtool_get_wol);
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 14d57d0..6339771 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1043,7 +1043,7 @@ int phy_suspend(struct phy_device *phydev)
 	if (wol.wolopts)
 		return -EBUSY;
 
-	if (phydrv->suspend)
+	if (phydev->drv && phydrv->suspend)
 		ret = phydrv->suspend(phydev);
 
 	if (ret)
@@ -1060,7 +1060,7 @@ int phy_resume(struct phy_device *phydev)
 	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
 	int ret = 0;
 
-	if (phydrv->resume)
+	if (phydev->drv && phydrv->resume)
 		ret = phydrv->resume(phydev);
 
 	if (ret)
@@ -1644,7 +1644,7 @@ static int phy_remove(struct device *dev)
 	phydev->state = PHY_DOWN;
 	mutex_unlock(&phydev->lock);
 
-	if (phydev->drv->remove)
+	if (phydev->drv && phydev->drv->remove)
 		phydev->drv->remove(phydev);
 	phydev->drv = NULL;
 
diff --git a/include/linux/phy.h b/include/linux/phy.h
index bd22670..fd235bb 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -769,6 +769,9 @@ int phy_stop_interrupts(struct phy_device *phydev);
 
 static inline int phy_read_status(struct phy_device *phydev)
 {
+	if (!phydev->drv)
+		return -EIO;
+
 	return phydev->drv->read_status(phydev);
 }
 
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