[PATCH 5.17 0462/1126] net: dsa: Avoid cross-chip syncing of VLAN filtering

Greg Kroah-Hartman
2022-04-05T08:36:06Z

From: Tobias Waldekranz <tobias@waldekranz.com>

[ 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@waldekranz.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/dsa/switch.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

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);
}
--
2.34.1