net: hsr: fix memory leak on slave unregistration by removing synced VLANs

When an HSR master device is brought UP, it auto-adds VLAN 0 via
vlan_vid0_add(), which propagates VID 0 to its slave devices (slave A and B).

If a slave device is later unregistered while HSR is active (e.g., during
netns cleanup or interface destruction), hsr_del_port() is called to
detach the slave port from the HSR master. However, hsr_del_port() currently
does not delete the VLAN IDs that were synced to the slave device by HSR.

As a result, the slave device retains a refcount on VID 0 (and any other
synced VLANs). When the slave device is destroyed, its vlan_info /
vlan_vid_info structure remains allocated, leading to a memory leak.

Fix this by calling vlan_vids_del_by_dev(port->dev, master->dev) in
hsr_del_port() before unlinking slave A or slave B ports, matching the
propagation logic in hsr_ndo_vlan_rx_add_vid() / hsr_ndo_vlan_rx_kill_vid()
and the cleanup behavior in bonding and team drivers.

Fixes: 1a8a63a5305e ("net: hsr: Add VLAN CTAG filter support")
Reported-by: syzbot+456957213f32970c0762@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6a4cb6ca.57639fcc.86d58.000b.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Reviewed-by: Felix Maurer <fmaurer@redhat.com>
Link: https://patch.msgid.link/20260721101240.995597-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/hsr/hsr_slave.c b/net/hsr/hsr_slave.c
index d9af9e65f72f07b1997b80c85db16d812fbda488..01c73b4b50ddd89afa74defa37fa83d40c401cf8 100644 (file)
--- a/net/hsr/hsr_slave.c
+++ b/net/hsr/hsr_slave.c
@@ -242,6 +242,8 @@ void hsr_del_port(struct hsr_port *port)
                netdev_rx_handler_unregister(port->dev);
                if (!port->hsr->fwd_offloaded)
                        dev_set_promiscuity(port->dev, -1);
+               if (port->type == HSR_PT_SLAVE_A || port->type == HSR_PT_SLAVE_B)
+                       vlan_vids_del_by_dev(port->dev, master->dev);
                netdev_upper_dev_unlink(port->dev, master->dev);
                if (hsr->prot_version == PRP_V1 &&
                    port->type == HSR_PT_SLAVE_B) {