[PATCH 4.2.y-ckt 281/305] net: phy: mdio-mux: Check return value of mdiobus_alloc()

4.2.8-ckt2 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Tobias Klauser <tklauser@distanz.ch>

commit 20b08e1a793d898f0f13040d5418ee0955f678cf upstream.

mdiobus_alloc() might return NULL, but its return value is not
checked in mdio_mux_init(). This could potentially lead to a NULL
pointer dereference. Fix it by checking the return value

Fixes: 0ca2997d1452 ("netdev/of/phy: Add MDIO bus multiplexer support.")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <redacted>
---
 drivers/net/phy/mdio-mux.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
index 4d4d25e..ac8a823 100644
--- a/drivers/net/phy/mdio-mux.c
+++ b/drivers/net/phy/mdio-mux.c

@@ -148,9 +148,14 @@ int mdio_mux_init(struct device *dev,
 		}
 		cb->bus_number = v;
 		cb->parent = pb;
+
 		cb->mii_bus = mdiobus_alloc();
+		if (!cb->mii_bus) {
+			ret_val = -ENOMEM;
+			of_node_put(child_bus_node);
+			break;
+		}
 		cb->mii_bus->priv = cb;
-
 		cb->mii_bus->irq = cb->phy_irq;
 		cb->mii_bus->name = "mdio_mux";
 		snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",

-- 
1.9.1