Re: [PATCH v2 09/19] Input: serio - use the compatibility driver attachment API

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [High] Input: serio: serio_bind_driver() fails with -EPERM under
  default boot policy
--

commit 3fd95316c0bff9166a7d599c0aa06fa861dbf4de
Author: Leon Romanovsky <leon@kernel.org>

Input: serio - use the compatibility driver attachment API

This commit replaces the manual driver connect and bind sequence in
serio_bind_driver() with device_driver_attach_full().

> diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
> index 54dd26249b027..b54072769ab68 100644
> --- a/drivers/input/serio/serio.c
> +++ b/drivers/input/serio/serio.c
> @@ -81,28 +81,10 @@ static int serio_match_port(const struct serio_device_id *ids, struct serio *ser
>  
>  static int serio_bind_driver(struct serio *serio, struct serio_driver *drv)
>  {
> -	int error;
> -
> -	if (serio_match_port(drv->id_table, serio)) {
> -
> -		serio->dev.driver = &drv->driver;
> -		if (serio_connect_driver(serio, drv)) {
> -			serio->dev.driver = NULL;
> -			return -ENODEV;
> -		}
> +	if (!serio_match_port(drv->id_table, serio))
> +		return 0;
>  
> -		error = device_bind_driver(&serio->dev);
> -		if (error) {
> -			dev_warn(&serio->dev,
> -				 "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
> -				 serio->phys, serio->name,
> -				 drv->description, error);
> -			serio_disconnect_driver(serio);
> -			serio->dev.driver = NULL;
> -			return error;
> -		}
> -	}
> -	return 0;
> +	return device_driver_attach_full(&drv->driver, &serio->dev);
>  }

[Severity: High]
As reported by Dmitry Torokhov on v1 [1], serio_bind_driver() is only
called for explicit user-initiated binding via the drvctl sysfs attribute,
and it was requested that this patch be dropped from the series.

In addition, does switching serio_bind_driver() to
device_driver_attach_full() break manual binding via drvctl on default
boots?  Later in this series (commit "driver core: Introduce a generic
device trust level" and commit "driver core: Accept device trust policy on
the kernel command line"), device_driver_attach_full() calls
device_trust_prepare_full(), which returns -EPERM unless
device_trust.default=full was passed on the kernel command line.  When
userspace writes a driver name such as serio_raw to drvctl, drvctl_store()
disconnects the existing driver via serio_disconnect_port() and then
serio_bind_driver() fails with -EPERM, leaving the port unbound.

[1] https://lore.kernel.org/r/auy2plYVi723Qt42@google.com

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261109-device-trust-core-v2-0-3b12d9a9f861@nvidia.com?part=9