net: dsa: Ensure that port array elements are initialized before being used

A network device notifier can be called for one or more of the created
slave devices before all slave devices have been registered. This can
result in a mismatch between ds->phys_port_mask and the registered devices
by the time the call is made, and it can result in a slave device being
added to a bridge before its entry in ds->ports[] has been initialized.

Rework the initialization code to initialize entries in ds->ports[] in
dsa_slave_create. With this change, dsa_slave_create no longer needs
to return slave_dev but can return an error code instead.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 13 insertions, 17 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 2173402d87e0..fc1813140be6 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -314,19 +314,15 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
          * Create network devices for physical switch ports.
          */
         for (i = 0; i < DSA_MAX_PORTS; i++) {
-                struct net_device *slave_dev;
-
                 if (!(ds->phys_port_mask & (1 << i)))
                         continue;
 
-                slave_dev = dsa_slave_create(ds, parent, i, pd->port_names[i]);
-                if (slave_dev == NULL) {
+                ret = dsa_slave_create(ds, parent, i, pd->port_names[i]);
+                if (ret < 0) {
                         netdev_err(dst->master_netdev, "[%d]: can't create dsa slave device for port %d(%s)\n",
                                    index, i, pd->port_names[i]);
-                        continue;
+                        ret = 0;
                 }
-
-                ds->ports[i] = slave_dev;
         }
 
 #ifdef CONFIG_NET_DSA_HWMON
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index dc9756d3154c..7eb1a6acd46c 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -53,9 +53,8 @@ extern char dsa_driver_version[];
 /* slave.c */
 extern const struct dsa_device_ops notag_netdev_ops;
 void dsa_slave_mii_bus_init(struct dsa_switch *ds);
-struct net_device *dsa_slave_create(struct dsa_switch *ds,
-                                    struct device *parent,
-                                    int port, char *name);
+int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
+                     int port, char *name);
 int dsa_slave_suspend(struct net_device *slave_dev);
 int dsa_slave_resume(struct net_device *slave_dev);
 
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index f23deadf42a0..5be4c928c9c9 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -605,9 +605,8 @@ int dsa_slave_resume(struct net_device *slave_dev)
         return 0;
 }
 
-struct net_device *
-dsa_slave_create(struct dsa_switch *ds, struct device *parent,
-                 int port, char *name)
+int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
+                     int port, char *name)
 {
         struct net_device *master = ds->dst->master_netdev;
         struct net_device *slave_dev;
@@ -617,7 +616,7 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
         slave_dev = alloc_netdev(sizeof(struct dsa_slave_priv), name,
                                  NET_NAME_UNKNOWN, ether_setup);
         if (slave_dev == NULL)
-                return slave_dev;
+                return -ENOMEM;
 
         slave_dev->features = master->vlan_features;
         slave_dev->ethtool_ops = &dsa_slave_ethtool_ops;
@@ -667,19 +666,21 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
         ret = dsa_slave_phy_setup(p, slave_dev);
         if (ret) {
                 free_netdev(slave_dev);
-                return NULL;
+                return ret;
         }
 
+        ds->ports[port] = slave_dev;
         ret = register_netdev(slave_dev);
         if (ret) {
                 netdev_err(master, "error %d registering interface %s\n",
                            ret, slave_dev->name);
                 phy_disconnect(p->phy);
+                ds->ports[port] = NULL;
                 free_netdev(slave_dev);
-                return NULL;
+                return ret;
         }
 
         netif_carrier_off(slave_dev);
 
-        return slave_dev;
+        return 0;
 }