FAILED: patch "[PATCH] net: dsa: bcm_sf2: Fix possible memory leak in" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.14.y
git checkout FETCH_HEAD
git cherry-pick -x 61b40cefe51af005c72dbdcf975a3d166c6e6406
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023102042-clinic-pruning-a3ca@gregkh' --subject-prefix 'PATCH 4.14.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 61b40cefe51af005c72dbdcf975a3d166c6e6406 Mon Sep 17 00:00:00 2001
From: Jinjie Ruan <[email protected]>
Date: Wed, 11 Oct 2023 11:24:19 +0800
Subject: [PATCH] net: dsa: bcm_sf2: Fix possible memory leak in
bcm_sf2_mdio_register()

In bcm_sf2_mdio_register(), the class_find_device() will call get_device() to increment reference count for priv->master_mii_bus->dev if of_mdio_find_bus() succeeds. If mdiobus_alloc() or mdiobus_register() fails, it will call get_device() twice without decrement reference count for the device. And it is the same if bcm_sf2_mdio_register() succeeds but fails in bcm_sf2_sw_probe(), or if bcm_sf2_sw_probe() succeeds. If the reference count has not decremented to zero, the dev related resource will not be freed.

So remove the get_device() in bcm_sf2_mdio_register(), and call put_device() if mdiobus_alloc() or mdiobus_register() fails and in bcm_sf2_mdio_unregister() to solve the issue.

And as Simon suggested, unwind from errors for bcm_sf2_mdio_register() and just return 0 if it succeeds to make it cleaner.

index 72374b066f64..cd1f240c90f3 100644
@@ -617,17 +617,16 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds)
 	dn = of_find_compatible_node(NULL, NULL, "brcm,unimac-mdio");
 	priv->master_mii_bus = of_mdio_find_bus(dn);
 	if (!priv->master_mii_bus) {
-		of_node_put(dn);
-		return -EPROBE_DEFER;
+		err = -EPROBE_DEFER;
+		goto err_of_node_put;
 	}
 
-	get_device(&priv->master_mii_bus->dev);
 	priv->master_mii_dn = dn;
 
 	priv->slave_mii_bus = mdiobus_alloc();
 	if (!priv->slave_mii_bus) {
-		of_node_put(dn);
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto err_put_master_mii_bus_dev;
 	}
 
 	priv->slave_mii_bus->priv = priv;

@@ -684,11 +683,17 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds)
 	}
 
 	err = mdiobus_register(priv->slave_mii_bus);
-	if (err && dn) {
-		mdiobus_free(priv->slave_mii_bus);
-		of_node_put(dn);
-	}
+	if (err && dn)
+		goto err_free_slave_mii_bus;
 
+	return 0;
+
+err_free_slave_mii_bus:
+	mdiobus_free(priv->slave_mii_bus);
+err_put_master_mii_bus_dev:
+	put_device(&priv->master_mii_bus->dev);
+err_of_node_put:
+	of_node_put(dn);
 	return err;
 }
 

@@ -696,6 +701,7 @@ static void bcm_sf2_mdio_unregister(struct bcm_sf2_priv *priv)
 {
 	mdiobus_unregister(priv->slave_mii_bus);
 	mdiobus_free(priv->slave_mii_bus);
+	put_device(&priv->master_mii_bus->dev);
 	of_node_put(priv->master_mii_dn);
 }