On 15/09/2026 13:23, Paolo Abeni wrote:
On 9/11/26 12:50 PM, Nikolay Aleksandrov wrote:
This is a follow-up of one of sashiko's pre-existing bug reports.
br_mst_set_state() calls switchdev_port_attr_set() for nonzero MSTIs
while holding rcu_read_lock() which invokes the blocking switchdev
notifier chain and may sleep. Nonzero MSTI changes come from netlink
with rtnl held. Move the switchdev call before entering the rcu section and
assert that rtnl is held.
The call cannot be deferred because netlink needs its error and extack.
Also DSA reads the old bridge MST state during the callback and checks it.
A deferred callback will be late and will see the updated state.
Fixes: 7ae9147f4312 ("net: bridge: mst: Notify switchdev drivers of MST state
changes")
Signed-off-by: Nikolay Aleksandrov <[email protected]>
Clashiko noted that the fixes tag looks inaccurate, should be:
Fixes: 3a7c1661ae1383 ("net: bridge: mst: fix vlan use-after-free")
do you agree? I can fix the tag while applying the patch no need to repost.
/P
Yeah, I agree. As Ido also noted, that is the correct commit id but it is
from the same set. :)
Thank you for taking care of this.
