Messages in this thread Patch in this message | | | Date | Tue, 25 Jan 2022 02:04:39 +0200 | From | Vladimir Oltean <> | Subject | Re: [PATCH net 2/2] net: dsa: Avoid cross-chip syncing of VLAN filtering |
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On Mon, Jan 24, 2022 at 10:09:44PM +0100, Tobias Waldekranz wrote: > Changes to VLAN filtering are not applicable to cross-chip > notifications.
Yes, it seems so. In a cross-chip setup, ports will individually leave the bridge, leaving every switch a chance to unset VLAN filtering. We have this check in dsa_port_vlan_filtering(), so it's easy to forget that the function is called more times than actually needed:
if (dsa_port_is_vlan_filtering(dp) == vlan_filtering) return 0;
Sorry.
> 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> > --- > 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; > + }
As net-next material, we could probably move this call to dsa_port_switchdev_unsync_attrs() where there's even a comment that references it, and do away with the targeted switch check.
> > return dsa_tag_8021q_bridge_leave(ds, info); > } > -- > 2.25.1 >
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
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