[PATCH net] net: mdio: validate parameter addr in mdiobus_get_phy()

[Heiner Kallweit <hkallweit1@gmail.com>]

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>
---
 drivers/net/phy/mdio_bus.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 902e1c88e..132dd1f90 100644
--- 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;
-- 
2.39.0