From 9043be310c6a4c5e57f7bba4b9870554eac7aa96 Mon Sep 17 00:00:00 2001 From: Jiale Yao Date: Mon, 19 Oct 2026 17:54:07 +0200 Subject: [PATCH] team: reject CAN, IEEE 802.15.4 and 6LoWPAN devices in team_port_add When the first port has a non-Ethernet type, team_setup_by_port() copies port_dev->type to the team device while netdev_priv() of the team device still holds a struct team. Several L2 stacks identify their devices by dev->type alone and then access type specific data that the team driver never sets up: - CAN protocols rely on the CAN mid-layer private data (ml_priv) - IEEE 802.15.4 code dereferences ieee802154_ptr and the mlme ops in ml_priv - the 6LoWPAN netdev notifier writes through lowpan_dev(dev) on NETDEV_DOWN and reads it on NETDEV_UP/NETDEV_CHANGE Enslaving such a device (e.g. vxcan, wpan0, lowpan0) therefore leads to NULL pointer dereferences or to writes into struct team. This is the same problem that syzbot reported for the bonding driver with a vxcan device enslaved to a bond master, which crashed in can_rx_unregister() and was fixed by commit 8ba68464e478 ("bonding: refuse to enslave CAN devices"). The team driver has the same gap. Reject ARPHRD_CAN, ARPHRD_IEEE802154, ARPHRD_IEEE802154_MONITOR and ARPHRD_6LOWPAN devices in team_port_add(). Link: https://lore.kernel.org/all/b58d98e0-8fe3-4e4e-b8a5-c1c7e647ccca@hartkopp.net/ Link: https://syzkaller.appspot.com/bug?extid=8ed98cbd0161632bce95 # bonding splat Fixes: 1d76efe1577b ("team: add support for non-ethernet devices") Signed-off-by: Jiale Yao Signed-off-by: Oliver Hartkopp Reviewed-by: Hangbin Liu Link: https://patch.msgid.link/20261019155407.61487-1-socketcan@hartkopp.net Signed-off-by: Jakub Kicinski --- drivers/net/team/team_core.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c index ca75f08e3c59..957cc7885d2f 100644 --- a/drivers/net/team/team_core.c +++ b/drivers/net/team/team_core.c @@ -1225,6 +1225,17 @@ static int team_port_add(struct team *team, struct net_device *port_dev, return -EINVAL; } + if (port_dev->type == ARPHRD_CAN || + port_dev->type == ARPHRD_IEEE802154 || + port_dev->type == ARPHRD_IEEE802154_MONITOR || + port_dev->type == ARPHRD_6LOWPAN) { + NL_SET_ERR_MSG(extack, + "CAN, IEEE 802.15.4 and 6LoWPAN devices can't be added as a team port"); + netdev_err(dev, "Device %s is CAN, IEEE 802.15.4 or 6LoWPAN. These device types can't be added as a team port\n", + portname); + return -EINVAL; + } + if (netif_is_team_port(port_dev)) { NL_SET_ERR_MSG(extack, "Device is already a port of a team device"); netdev_err(dev, "Device %s is already a port "