bonding: fix multicast MAC address synchronization

There is a corner case where the NS (Neighbor Solicitation) target is set to
an invalid or unreachable address. In such cases, all the slave links are
marked as down and set to backup. This causes the bond to add multicast MAC
addresses to all slaves.

However, bond_ab_arp_probe() later tries to activate a carrier on slave and
sets it as active. If we subsequently change or clear the NS targets, the
call to bond_slave_ns_maddrs_del() on this interface will fail because it
is still marked active, and the multicast MAC address will remain.

To fix this issue, move the NS multicast address add/remove logic into
bond_set_slave_state() to ensure multicast MAC addresses are updated
synchronously whenever the slave state changes.

Note: The call to bond_slave_ns_maddrs_del() in __bond_release_one() is
kept, as it is still required to clean up multicast MAC addresses when
a slave is removed.

Fixes: 8eb3616 ("bonding: add ns target multicast address to slave device")
Reported-by: Liang Li <[email protected]>
Signed-off-by: Hangbin Liu <[email protected]>
Signed-off-by: NipaLocal <nipa@local>

Author: liuhangbin

drivers/net/bonding/bond_main.c

@@ -1001,8 +1001,6 @@ static void bond_hw_addr_swap(struct bonding *bond, struct slave *new_active,
 
 		if (bond->dev->flags & IFF_UP)
 			bond_hw_addr_flush(bond->dev, old_active->dev);
-
-		bond_slave_ns_maddrs_add(bond, old_active);
 	}
 
 	if (new_active) {
@@ -1019,8 +1017,6 @@ static void bond_hw_addr_swap(struct bonding *bond, struct slave *new_active,
 			dev_mc_sync(new_active->dev, bond->dev);
 			netif_addr_unlock_bh(bond->dev);
 		}
-
-		bond_slave_ns_maddrs_del(bond, new_active);
 	}
 }
 
@@ -2356,11 +2352,6 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 	bond_compute_features(bond);
 	bond_set_carrier(bond);
 
-	/* Needs to be called before bond_select_active_slave(), which will
-	 * remove the maddrs if the slave is selected as active slave.
-	 */
-	bond_slave_ns_maddrs_add(bond, new_slave);
-
 	if (bond_uses_primary(bond)) {
 		block_netpoll_tx();
 		bond_select_active_slave(bond);

include/net/bonding.h

@@ -385,7 +385,14 @@ static inline void bond_set_slave_state(struct slave *slave,
 	if (slave->backup == slave_state)
 		return;
 
+	if (slave_state == BOND_STATE_ACTIVE)
+		bond_slave_ns_maddrs_del(slave->bond, slave);
+
 	slave->backup = slave_state;
+
+	if (slave_state == BOND_STATE_BACKUP)
+		bond_slave_ns_maddrs_add(slave->bond, slave);
+
 	if (notify) {
 		bond_lower_state_changed(slave);
 		bond_queue_slave_event(slave);