net: phylib: ensure phy device drivers do not match by DT

PHYLIB device drivers must match by either numerical PHY ID or by their
.match_phy_device method. Matching by DT is not permitted.

Link: https://lore.kernel.org/r/2b1dc053-8c9a-e3e4-b450-eecdfca3fe16@gmail.comTested-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy_device.c

@@ -3146,6 +3146,16 @@ int phy_driver_register(struct phy_driver *new_driver, struct module *owner)
 		return -EINVAL;
 	}
 
+	/* PHYLIB device drivers must not match using a DT compatible table
+	 * as this bypasses our checks that the mdiodev that is being matched
+	 * is backed by a struct phy_device. If such a case happens, we will
+	 * make out-of-bounds accesses and lockup in phydev->lock.
+	 */
+	if (WARN(new_driver->mdiodrv.driver.of_match_table,
+		 "%s: driver must not provide a DT match table\n",
+		 new_driver->name))
+		return -EINVAL;
+
 	new_driver->mdiodrv.flags |= MDIO_DEVICE_IS_PHY;
 	new_driver->mdiodrv.driver.name = new_driver->name;
 	new_driver->mdiodrv.driver.bus = &mdio_bus_type;