net: dsa: Avoid cross-chip syncing of VLAN filtering

Changes to VLAN filtering are not applicable to cross-chip
notifications.

On a system like this:

.-----.   .-----.   .-----.
| sw1 +---+ sw2 +---+ sw3 |
'-1-2-'   '-1-2-'   '-1-2-'

Before this change, upon sw1p1 leaving a bridge, a call to
dsa_port_vlan_filtering would also be made to sw2p1 and sw3p1.

In this scenario:

.---------.   .-----.   .-----.
|   sw1   +---+ sw2 +---+ sw3 |
'-1-2-3-4-'   '-1-2-'   '-1-2-'

When sw1p4 would leave a bridge, dsa_port_vlan_filtering would be
called for sw2 and sw3 with a non-existing port - leading to array
out-of-bounds accesses and crashes on mv88e6xxx.

Fixes: d371b7c92d19 ("net: dsa: Unset vlan_filtering when ports leave the bridge")
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index 9f9b70d6070a3ff6fa22fc3fe9aba5f38ceaf558..517cc83d13cc89699004525df54379e4cb21fd50 100644 (file)
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c
@@ -180,9 +180,11 @@ static int dsa_switch_bridge_leave(struct dsa_switch *ds,
                                                info->sw_index, info->port,
                                                info->bridge);
 
-       err = dsa_switch_sync_vlan_filtering(ds, info);
-       if (err)
-               return err;
+       if (ds->dst->index == info->tree_index && ds->index == info->sw_index) {
+               err = dsa_switch_sync_vlan_filtering(ds, info);
+               if (err)
+                       return err;
+       }
 
        return dsa_tag_8021q_bridge_leave(ds, info);
 }