Re: [PATCH net-next 07/13] dpaa2-switch: check early if an FDB entry should be added

[Ioana Ciornei]

On Wed, May 06, 2026 at 06:15:34PM +0300, Ioana Ciornei wrote:
> Instead of waiting until the last moment to check if an FDB entry should
> be added to HW, move the check earlier (before even scheduling the work
> item) so that we don't just waste time.
> 
> Signed-off-by: Ioana Ciornei <ioana.ciornei@xxxxxxx>
> ---
>  drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
> index 476ee8b46921..a057fd85bd27 100644

(...)

>  	if (!dpaa2_switch_port_dev_check(dev))
>  		return NOTIFY_DONE;
>  
> +	if (!fdb_info->added_by_user || fdb_info->is_local)
> +		return NOTIFY_DONE;
> +

Sashiko notes:

	This problem wasn't introduced by this patch, but looking at the
	surrounding context in this function, is there a pre-existing
	out-of-bounds read issue?

	Could reading port_priv->ethsw_data happen before ensuring the
	device belongs to the dpaa2-switch driver?

	Since switchdev notifiers are called globally for all network
	devices, an event on a device with zero private data (like a
	dummy interface) would cause netdev_priv(dev) to point to the
	end of the device allocation.

	If the allocation ends at a page boundary, would accessing
	ethsw_data trigger a KASAN panic or a page fault when an
	unprivileged user creates a dummy interface in a network
	namespace and adds an FDB entry?

I don't think that can happen since dpaa2_switch_port_fdb_event() is
called using switchdev_handle_fdb_event_to_device() which checks if the
interface is a dpaa2-switch one using the dpaa2_switch_port_dev_check()
callback.