[PATCH] net: dsa: microchip: Fix parent_mdio_bus reference leak in ksz_mdio_register()

[Wentao Liang]

of_mdio_find_bus() returns a mii_bus whose embedded struct device has
its reference count incremented. When ksz_mdio_register() fails after
the parent bus has been stored in dev->parent_mdio_bus, that reference
is never dropped, so the parent MDIO bus device leaks on every probe
failure.

Drop the reference before returning from the error path.

Fixes: 9afaf0eec2ab ("net: dsa: microchip: Refactor MDIO handling for side MDIO access")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Wentao Liang <vulab@xxxxxxxxxxx>
---
 drivers/net/dsa/microchip/ksz_common.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 144373e13bea..fcf3a29ffca3 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -2807,6 +2807,11 @@ static int ksz_mdio_register(struct ksz_device *dev)
 	}
 
 put_mdio_node:
+	if (ret && dev->parent_mdio_bus) {
+		put_device(&dev->parent_mdio_bus->dev);
+		dev->parent_mdio_bus = NULL;
+	}
+
 	of_node_put(mdio_np);
 	of_node_put(parent_bus_node);
 
-- 
2.34.1