net: mdiobus: fix an OF node reference leak

JIRA: https://issues.redhat.com/browse/RHEL-78049

commit 572af9f
Author: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Date:   Wed Dec 18 12:51:06 2024 +0900

    net: mdiobus: fix an OF node reference leak

    fwnode_find_mii_timestamper() calls of_parse_phandle_with_fixed_args()
    but does not decrement the refcount of the obtained OF node. Add an
    of_node_put() call before returning from the function.

    This bug was detected by an experimental static analysis tool that I am
    developing.

    Fixes: bc1bee3 ("net: mdiobus: Introduce fwnode_mdiobus_register_phy()")
    Signed-off-by: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
    Reviewed-by: Andrew Lunn <andrew@lunn.ch>
    Link: https://patch.msgid.link/20241218035106.1436405-1-joe@pf.is.s.u-tokyo.ac.jp
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Signed-off-by: Jared Kangas <jkangas@redhat.com>

Author: rh-jkangas

drivers/net/mdio/fwnode_mdio.c

@@ -40,6 +40,7 @@ fwnode_find_pse_control(struct fwnode_handle *fwnode)
 static struct mii_timestamper *
 fwnode_find_mii_timestamper(struct fwnode_handle *fwnode)
 {
+	struct mii_timestamper *mii_ts;
 	struct of_phandle_args arg;
 	int err;
 
@@ -53,10 +54,16 @@ fwnode_find_mii_timestamper(struct fwnode_handle *fwnode)
 	else if (err)
 		return ERR_PTR(err);
 
-	if (arg.args_count != 1)
-		return ERR_PTR(-EINVAL);
+	if (arg.args_count != 1) {
+		mii_ts = ERR_PTR(-EINVAL);
+		goto put_node;
+	}
+
+	mii_ts = register_mii_timestamper(arg.np, arg.args[0]);
 
-	return register_mii_timestamper(arg.np, arg.args[0]);
+put_node:
+	of_node_put(arg.np);
+	return mii_ts;
 }
 
 int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,