net: systemport: Check DSA notifier master against ourself

Check that the master network device that is signaled through the DSA
notifier is actually going to be ourself, otherwise, we could just be
de-referencing garbage from other drivers.

Fixes: 84ff33eeb23d ("net: systemport: Establish DSA network device queue mapping")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -2046,6 +2046,21 @@ static u16 bcm_sysport_select_queue(struct net_device *dev, struct sk_buff *skb,
 	return tx_ring->index;
 }
 
+static const struct net_device_ops bcm_sysport_netdev_ops = {
+	.ndo_start_xmit		= bcm_sysport_xmit,
+	.ndo_tx_timeout		= bcm_sysport_tx_timeout,
+	.ndo_open		= bcm_sysport_open,
+	.ndo_stop		= bcm_sysport_stop,
+	.ndo_set_features	= bcm_sysport_set_features,
+	.ndo_set_rx_mode	= bcm_sysport_set_rx_mode,
+	.ndo_set_mac_address	= bcm_sysport_change_mac,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_poll_controller	= bcm_sysport_poll_controller,
+#endif
+	.ndo_get_stats64	= bcm_sysport_get_stats64,
+	.ndo_select_queue	= bcm_sysport_select_queue,
+};
+
 static int bcm_sysport_map_queues(struct net_device *dev,
 				  struct dsa_notifier_register_info *info)
 {
@@ -2061,6 +2076,9 @@ static int bcm_sysport_map_queues(struct net_device *dev,
 	if (info->switch_number)
 		return 0;
 
+	if (dev->netdev_ops != &bcm_sysport_netdev_ops)
+		return 0;
+
 	port = info->port_number;
 	slave_dev = info->info.dev;
 
@@ -2112,21 +2130,6 @@ static int bcm_sysport_dsa_notifier(struct notifier_block *unused,
 	return notifier_from_errno(bcm_sysport_map_queues(info->master, info));
 }
 
-static const struct net_device_ops bcm_sysport_netdev_ops = {
-	.ndo_start_xmit		= bcm_sysport_xmit,
-	.ndo_tx_timeout		= bcm_sysport_tx_timeout,
-	.ndo_open		= bcm_sysport_open,
-	.ndo_stop		= bcm_sysport_stop,
-	.ndo_set_features	= bcm_sysport_set_features,
-	.ndo_set_rx_mode	= bcm_sysport_set_rx_mode,
-	.ndo_set_mac_address	= bcm_sysport_change_mac,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= bcm_sysport_poll_controller,
-#endif
-	.ndo_get_stats64	= bcm_sysport_get_stats64,
-	.ndo_select_queue	= bcm_sysport_select_queue,
-};
-
 #define REV_FMT	"v%2x.%02x"
 
 static const struct bcm_sysport_hw_params bcm_sysport_params[] = {