Re: [PATCH net v4] team: reject CAN, IEEE 802.15.4 and 6LoWPAN devices in team_port_add

[Hangbin Liu <hangbin.liu@linux.dev>]

On Wed, Oct 14, 2026 at 04:33:09PM +0200, Oliver Hartkopp wrote:
> From: Jiale Yao <yaojiale02@163.com>
> 
> 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.
> 
> Reject ARPHRD_CAN, ARPHRD_IEEE802154, ARPHRD_IEEE802154_MONITOR and
> ARPHRD_6LOWPAN devices in team_port_add(). The bonding driver has
> rejected CAN devices since commit 8ba68464e478 ("bonding: refuse to
> enslave CAN devices").
> 
> Link: https://lore.kernel.org/all/b58d98e0-8fe3-4e4e-b8a5-c1c7e647ccca@hartkopp.net/
> Fixes: 1d76efe1577b ("team: add support for non-ethernet devices")
> Assisted-by: Claude:deepseek-v4-pro
> Signed-off-by: Jiale Yao <yaojiale02@163.com>
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
> ---
> v4: [Hartkopp] also reject ARPHRD_6LOWPAN as reported by Sashiko AI
>     review, reworded commit message (bonding only rejects CAN)
> v3: [Hartkopp] fixed indention and compilation as reported by kernel test robot
> ---
>  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
> --- a/drivers/net/team/team_core.c
> +++ b/drivers/net/team/team_core.c
> @@ -1223,10 +1223,21 @@ static int team_port_add(struct team *team, struct net_device *port_dev,
>  		netdev_err(dev, "Device %s is loopback device. Loopback devices can't be added as a team port\n",
>  			   portname);
>  		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 "
>  				"of a team device\n", portname);
>  		return -EBUSY;
> --
> 2.53.0
> 

Thanks for the followup.

Reviewed-by: Hangbin Liu <liuhangbin@kylinos.cn>