target/linux/generic/backport-5.4/781-v5.18-2-net-dsa-Avoid-cross-chip-syncing-of-VLAN-filtering.patch

   1 From f6edb463510bd936f143907468fc0bf0762b87bf Mon Sep 17 00:00:00 2001
   2 From: Tobias Waldekranz <tobias@waldekranz.com>
   3 Date: Mon, 24 Jan 2022 22:09:44 +0100
   4 Subject: [PATCH 5.4 2/2] net: dsa: Avoid cross-chip syncing of VLAN filtering
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 commit 108dc8741c203e9d6ce4e973367f1bac20c7192b upstream.
  10
  11 Changes to VLAN filtering are not applicable to cross-chip
  12 notifications.
  13
  14 On a system like this:
  15
  16 .-----.   .-----.   .-----.
  17 | sw1 +---+ sw2 +---+ sw3 |
  18 '-1-2-'   '-1-2-'   '-1-2-'
  19
  20 Before this change, upon sw1p1 leaving a bridge, a call to
  21 dsa_port_vlan_filtering would also be made to sw2p1 and sw3p1.
  22
  23 In this scenario:
  24
  25 .---------.   .-----.   .-----.
  26 |   sw1   +---+ sw2 +---+ sw3 |
  27 '-1-2-3-4-'   '-1-2-'   '-1-2-'
  28
  29 When sw1p4 would leave a bridge, dsa_port_vlan_filtering would be
  30 called for sw2 and sw3 with a non-existing port - leading to array
  31 out-of-bounds accesses and crashes on mv88e6xxx.
  32
  33 Fixes: d371b7c92d19 ("net: dsa: Unset vlan_filtering when ports leave the bridge")
  34 Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
  35 Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
  36 Signed-off-by: David S. Miller <davem@davemloft.net>
  37 Signed-off-by: Marek Behún <kabel@kernel.org>
  38 ---
  39  net/dsa/switch.c | 8 +++++---
  40  1 file changed, 5 insertions(+), 3 deletions(-)
  41
  42 diff --git a/net/dsa/switch.c b/net/dsa/switch.c
  43 index dd71e3301b27..f517d6d7efa2 100644
  44 --- a/net/dsa/switch.c
  45 +++ b/net/dsa/switch.c
  46 @@ -112,9 +112,11 @@ static int dsa_switch_bridge_leave(struct dsa_switch *ds,
  47                 ds->ops->crosschip_bridge_leave(ds, info->sw_index, info->port,
  48                                                 info->br);
  49
  50 -       err = dsa_switch_sync_vlan_filtering(ds, info);
  51 -       if (err)
  52 -               return err;
  53 +       if (ds->index == info->sw_index) {
  54 +               err = dsa_switch_sync_vlan_filtering(ds, info);
  55 +               if (err)
  56 +                       return err;
  57 +       }
  58
  59         return 0;
  60  }
  61 --
  62 2.34.1
  63