Patch "net: dsa: Avoid cross-chip syncing of VLAN filtering" has been added to the 5.17-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 5.17-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-dsa-avoid-cross-chip-syncing-of-vlan-filtering.patch
and it can be found in the queue-5.17 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e5e27fdd565f5366b50301afedb0d9654804cc7d
Author: Tobias Waldekranz <tobias@xxxxxxxxxxxxxx>
Date:   Mon Jan 24 22:09:44 2022 +0100

    net: dsa: Avoid cross-chip syncing of VLAN filtering
    
    [ Upstream commit 108dc8741c203e9d6ce4e973367f1bac20c7192b ]
    
    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@xxxxxxxxxxxxxx>
    Reviewed-by: Vladimir Oltean <olteanv@xxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index 9f9b70d6070a..517cc83d13cc 100644
--- 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);
 }