Re: [PATCH v2 net] net: hsr: fix memory leak on slave unregistration by removing synced VLANs

[Felix Maurer <fmaurer@redhat.com>]

On Tue, Jul 21, 2026 at 10:12:40AM +0000, Eric Dumazet wrote:
> 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>
> Cc: Felix Maurer <fmaurer@redhat.com>
> Cc: Fernando Fernandez Mancera <fmancera@suse.de>

Looks good to me, thank you!

Reviewed-by: Felix Maurer <fmaurer@redhat.com>