[PATCH net] of: of_mdio: Ensure mdio device is a PHY

[Andrew Lunn <andrew@lunn.ch>]

of_phy_find_device() is used to find the phy device associated with a
device node. It is expected the node is for a PHY device, but in fact
it could of been probed as a generic MDIO device. Ensure the device is
a PHY before returning it.

Fixes: a9049e0c513c ("mdio: Add support for mdio drivers.")
Reported-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---

This is only 1/2 the fix. It will stop the NULL pointer dereference in
the mutex code, but the Ethernet device probe is likely to return an
error when it cannot find its PHY.
---
 drivers/of/of_mdio.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index 86829f8064a6..b5aa004a24b6 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -256,11 +256,19 @@ static int of_phy_match(struct device *dev, void *phy_np)
 struct phy_device *of_phy_find_device(struct device_node *phy_np)
 {
 	struct device *d;
+	struct mdio_device *mdiodev;
+
 	if (!phy_np)
 		return NULL;
 
 	d = bus_find_device(&mdio_bus_type, NULL, phy_np, of_phy_match);
-	return d ? to_phy_device(d) : NULL;
+	if (d) {
+		mdiodev = to_mdio_device(d);
+		if (mdiodev->flags & MDIO_DEVICE_FLAG_PHY)
+			return to_phy_device(d);
+	}
+
+	return NULL;
 }
 EXPORT_SYMBOL(of_phy_find_device);
 
-- 
2.7.0