net: phy: Check against net_device being NULL

In general, we don't want MAC drivers calling phy_attach_direct with the
net_device being NULL. Add checks against this in all the functions
calling it: phy_attach() and phy_connect_direct().
Signed-off-by: NIoana Ciornei <ioana.ciornei@nxp.com>
Suggested-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/phy_device.c

@@ -948,6 +948,9 @@ int phy_connect_direct(struct net_device *dev, struct phy_device *phydev,
 {
 	int rc;
 
+	if (!dev)
+		return -EINVAL;
+
 	rc = phy_attach_direct(dev, phydev, phydev->dev_flags, interface);
 	if (rc)
 		return rc;
@@ -1307,6 +1310,9 @@ struct phy_device *phy_attach(struct net_device *dev, const char *bus_id,
 	struct device *d;
 	int rc;
 
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
 	/* Search the list of PHY devices on the mdio bus for the
 	 * PHY with the requested name
 	 */