[PATCH RFT net-next] 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.com
Signed-off-by: Russell King (Oracle) <redacted>
---
Tested locally in SolidRun Clearfog, DSA switch and PHY get probed
correctly. Further testing welcomed.

 drivers/net/phy/phy_device.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index ba5ad86ec826..ba295b8ad8fe 100644
--- a/drivers/net/phy/phy_device.c
+++ b/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;

-- 
2.30.2

On Thu, Sep 30, 2021 at 03:54:49PM +0100, Russell King (Oracle) wrote:

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.com
Signed-off-by: Russell King (Oracle) <redacted>

Tested-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew