net: mscc: ocelot: fix error handling bugs in mscc_ocelot_init_ports()

There are several error handling bugs in mscc_ocelot_init_ports().  I
went through the code, and carefully audited it and made fixes and
cleanups.

1) The ocelot_probe_port() function didn't have a mirror release function
   so it was hard to follow.  I created the ocelot_release_port()
   function.
2) In the ocelot_probe_port() function, if the register_netdev() call
   failed, then it lead to a double free_netdev(dev) bug.  Fix this by
   setting "ocelot->ports[port] = NULL" on the error path.
3) I was concerned that the "port" which comes from of_property_read_u32()
   might be out of bounds so I added a check for that.
4) In the original code if ocelot_regmap_init() failed then the driver
   tried to continue but I think that should be a fatal error.
5) If ocelot_probe_port() failed then the most recent devlink was leaked.
   The fix for mostly came Vladimir Oltean.  Get rid of "registered_ports"
   and just set a bit in "devlink_ports_registered" to say when the
   devlink port has been registered (and needs to be unregistered on
   error).  There are fewer than 32 ports so a u32 is large enough for
   this purpose.
6) The error handling if the final ocelot_port_devlink_init() failed had
   two problems.  The "while (port-- >= 0)" loop should have been
   "--port" pre-op instead of a post-op to avoid a buffer underflow.
   The "if (!registered_ports[port])" condition was reversed leading to
   resource leaks and double frees.

Fixes: 6c30384 ("net: mscc: ocelot: register devlink ports")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/YBkXhqRxHtRGzSnJ@mwanda
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mscc/ocelot.h

@@ -121,6 +121,7 @@ void ocelot_port_writel(struct ocelot_port *port, u32 val, u32 reg);
 
 int ocelot_probe_port(struct ocelot *ocelot, int port, struct regmap *target,
 		      struct phy_device *phy);
+void ocelot_release_port(struct ocelot_port *ocelot_port);
 int ocelot_devlink_init(struct ocelot *ocelot);
 void ocelot_devlink_teardown(struct ocelot *ocelot);
 int ocelot_port_devlink_init(struct ocelot *ocelot, int port,

drivers/net/ethernet/mscc/ocelot_net.c

@@ -1283,7 +1283,19 @@ int ocelot_probe_port(struct ocelot *ocelot, int port, struct regmap *target,
 	if (err) {
 		dev_err(ocelot->dev, "register_netdev failed\n");
 		free_netdev(dev);
+		ocelot->ports[port] = NULL;
+		return err;
 	}
 
-	return err;
+	return 0;
+}
+
+void ocelot_release_port(struct ocelot_port *ocelot_port)
+{
+	struct ocelot_port_private *priv = container_of(ocelot_port,
+						struct ocelot_port_private,
+						port);
+
+	unregister_netdev(priv->dev);
+	free_netdev(priv->dev);
 }

drivers/net/ethernet/mscc/ocelot_vsc7514.c

@@ -1064,29 +1064,23 @@ static void mscc_ocelot_release_ports(struct ocelot *ocelot)
 	int port;
 
 	for (port = 0; port < ocelot->num_phys_ports; port++) {
-		struct ocelot_port_private *priv;
 		struct ocelot_port *ocelot_port;
 
 		ocelot_port = ocelot->ports[port];
 		if (!ocelot_port)
 			continue;
 
 		ocelot_deinit_port(ocelot, port);
-
-		priv = container_of(ocelot_port, struct ocelot_port_private,
-				    port);
-
-		unregister_netdev(priv->dev);
-		free_netdev(priv->dev);
+		ocelot_release_port(ocelot_port);
 	}
 }
 
 static int mscc_ocelot_init_ports(struct platform_device *pdev,
 				  struct device_node *ports)
 {
 	struct ocelot *ocelot = platform_get_drvdata(pdev);
+	u32 devlink_ports_registered = 0;
 	struct device_node *portnp;
-	bool *registered_ports;
 	int port, err;
 	u32 reg;
 
@@ -1102,11 +1096,6 @@ static int mscc_ocelot_init_ports(struct platform_device *pdev,
 	if (!ocelot->devlink_ports)
 		return -ENOMEM;
 
-	registered_ports = kcalloc(ocelot->num_phys_ports, sizeof(bool),
-				   GFP_KERNEL);
-	if (!registered_ports)
-		return -ENOMEM;
-
 	for_each_available_child_of_node(ports, portnp) {
 		struct ocelot_port_private *priv;
 		struct ocelot_port *ocelot_port;
@@ -1123,14 +1112,22 @@ static int mscc_ocelot_init_ports(struct platform_device *pdev,
 			continue;
 
 		port = reg;
+		if (port < 0 || port >= ocelot->num_phys_ports) {
+			dev_err(ocelot->dev,
+				"invalid port number: %d >= %d\n", port,
+				ocelot->num_phys_ports);
+			continue;
+		}
 
 		snprintf(res_name, sizeof(res_name), "port%d", port);
 
 		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 						   res_name);
 		target = ocelot_regmap_init(ocelot, res);
-		if (IS_ERR(target))
-			continue;
+		if (IS_ERR(target)) {
+			err = PTR_ERR(target);
+			goto out_teardown;
+		}
 
 		phy_node = of_parse_phandle(portnp, "phy-handle", 0);
 		if (!phy_node)
@@ -1147,15 +1144,14 @@ static int mscc_ocelot_init_ports(struct platform_device *pdev,
 			of_node_put(portnp);
 			goto out_teardown;
 		}
+		devlink_ports_registered |= BIT(port);
 
 		err = ocelot_probe_port(ocelot, port, target, phy);
 		if (err) {
 			of_node_put(portnp);
 			goto out_teardown;
 		}
 
-		registered_ports[port] = true;
-
 		ocelot_port = ocelot->ports[port];
 		priv = container_of(ocelot_port, struct ocelot_port_private,
 				    port);
@@ -1208,23 +1204,16 @@ static int mscc_ocelot_init_ports(struct platform_device *pdev,
 
 	/* Initialize unused devlink ports at the end */
 	for (port = 0; port < ocelot->num_phys_ports; port++) {
-		if (registered_ports[port])
+		if (devlink_ports_registered & BIT(port))
 			continue;
 
 		err = ocelot_port_devlink_init(ocelot, port,
 					       DEVLINK_PORT_FLAVOUR_UNUSED);
-		if (err) {
-			while (port-- >= 0) {
-				if (!registered_ports[port])
-					continue;
-				ocelot_port_devlink_teardown(ocelot, port);
-			}
-
+		if (err)
 			goto out_teardown;
-		}
-	}
 
-	kfree(registered_ports);
+		devlink_ports_registered |= BIT(port);
+	}
 
 	return 0;
 
@@ -1233,12 +1222,9 @@ static int mscc_ocelot_init_ports(struct platform_device *pdev,
 	mscc_ocelot_release_ports(ocelot);
 	/* Tear down devlink ports for the registered network interfaces */
 	for (port = 0; port < ocelot->num_phys_ports; port++) {
-		if (!registered_ports[port])
-			continue;
-
-		ocelot_port_devlink_teardown(ocelot, port);
+		if (devlink_ports_registered & BIT(port))
+			ocelot_port_devlink_teardown(ocelot, port);
 	}
-	kfree(registered_ports);
 	return err;
 }