From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	syzbot+456957213f32970c0762@syzkaller.appspotmail.com,
	Eric Dumazet <edumazet@google.com>,
	Fernando Fernandez Mancera <fmancera@suse.de>,
	Felix Maurer <fmaurer@redhat.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 117/456] net: hsr: fix memory leak on slave unregistration by removing synced VLANs
Date: Mon, 17 Aug 2026 15:28:27 +0200
Message-ID: <20260817132544.664467350@linuxfoundation.org>
In-Reply-To: <20260817132539.792407575@linuxfoundation.org>
References: <20260817132539.792407575@linuxfoundation.org>
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5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit dcf15eaf5641812f1cfc5e96537380132a7da89d ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 b8230faa567f77..58e757dc555461 100644
--- a/net/hsr/hsr_slave.c
+++ b/net/hsr/hsr_slave.c
@@ -228,6 +228,8 @@ 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);
 	}
 
-- 
2.53.0