net: mdio: validate parameter addr in mdiobus_get_phy()

The caller may pass any value as addr, what may result in an out-of-bounds
access to array mdio_map. One existing case is stmmac_init_phy() that
may pass -1 as addr. Therefore validate addr before using it.

Fixes: 7f854420fbfe ("phy: Add API for {un}registering an mdio device to a bus.")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/cdf664ea-3312-e915-73f8-021678d08887@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 1cd604c..16e021b 100644 (file)
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -108,7 +108,12 @@ EXPORT_SYMBOL(mdiobus_unregister_device);
 
 struct phy_device *mdiobus_get_phy(struct mii_bus *bus, int addr)
 {
-       struct mdio_device *mdiodev = bus->mdio_map[addr];
+       struct mdio_device *mdiodev;
+
+       if (addr < 0 || addr >= ARRAY_SIZE(bus->mdio_map))
+               return NULL;
+
+       mdiodev = bus->mdio_map[addr];
 
        if (!mdiodev)
                return NULL;