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

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

[Eric Dumazet]

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>
---
v2: incorporated Sashiko's feedback
v1: https://lore.kernel.org/netdev/20260707082327.3238690-1-edumazet@google.com/

 net/hsr/hsr_slave.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/hsr/hsr_slave.c b/net/hsr/hsr_slave.c
index d9af9e65f72f07b1997b80c85db16d812fbda488..01c73b4b50ddd89afa74defa37fa83d40c401cf8 100644
--- 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) {
-- 
2.55.0.229.g6434b31f56-goog

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

[Fernando Fernandez Mancera]

On 7/21/26 12:12 PM, 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>

Nice catch on Sashiko's feedback, thanks.

Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>

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

[Felix Maurer]

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>