This is a note to let you know that I've just added the patch titled net: dsa: avoid refcount warnings when ->port_{fdb,mdb}_del returns error to the 5.14-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-refcount-warnings-when-port_-fdb-mdb-_.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f6a5784c7989b01c92c180669d9d70cfb613c9c3 Author: Vladimir Oltean <vladimir.oltean@xxxxxxx> Date: Sun Oct 24 20:17:48 2021 +0300 net: dsa: avoid refcount warnings when ->port_{fdb,mdb}_del returns error [ Upstream commit 232deb3f9567ce37d99b8616a6c07c1fc0436abf ] At present, when either of ds->ops->port_fdb_del() or ds->ops->port_mdb_del() return a non-zero error code, we attempt to save the day and keep the data structure associated with that switchdev object, as the deletion procedure did not complete. However, the way in which we do this is suspicious to the checker in lib/refcount.c, who thinks it is buggy to increment a refcount that became zero, and that this is indicative of a use-after-free. Fixes: 161ca59d39e9 ("net: dsa: reference count the MDB entries at the cross-chip notifier level") Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx> 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 9ef9125713321..41f62c3ab9671 100644 --- a/net/dsa/switch.c +++ b/net/dsa/switch.c @@ -243,7 +243,7 @@ static int dsa_switch_do_mdb_del(struct dsa_switch *ds, int port, err = ds->ops->port_mdb_del(ds, port, mdb); if (err) { - refcount_inc(&a->refcount); + refcount_set(&a->refcount, 1); return err; } @@ -308,7 +308,7 @@ static int dsa_switch_do_fdb_del(struct dsa_switch *ds, int port, err = ds->ops->port_fdb_del(ds, port, addr, vid); if (err) { - refcount_inc(&a->refcount); + refcount_set(&a->refcount, 1); return err; }