Re: [PATCH v2] staging: greybus: light: fix leak of cdev->name

[Rui Miguel Silva <rui.silva@linaro.org>]

Hi Cong,
Thanks for the patch.

On Sun Aug 2, 2026 at 7:01 AM WEST, Cong Nguyen wrote:

> gb_lights_channel_config() builds the LED classdev name with kasprintf()
> and stores it in cdev->name for every channel during the configuration
> phase, which runs before the channel is registered.
>
> That name was only released by __gb_lights_led_unregister(), i.e. only for
> a normal LED channel that was actually registered. It was therefore leaked
> in two cases:
>
>   - a channel that is configured but never registered, e.g.
>     channel_attr_groups_set() fails, the flash configuration fails, or a
>     later channel in the same light fails to configure and the whole light
>     is torn down; the release path calls gb_lights_channel_unregister()
>     (which returns early because the channel is not registered) and then
>     gb_lights_channel_free();
>
>   - a flash, torch or indicator channel, whose unregister path
>     (__gb_lights_flash_led_unregister()) never releases cdev->name at all,
>     so the name leaks even on a successful teardown.
>
> cdev->name is a configuration-phase allocation, like channel->color_name
> and channel->mode_name. Free it in gb_lights_channel_free() next to
> those, since that runs unconditionally on every teardown path, and drop
> the special case free from __gb_lights_led_unregister().
> gb_lights_channel_unregister() is only ever called from
> gb_lights_channel_release(), immediately followed by
> gb_lights_channel_free(), so the name is still released on the registered
> path and is freed exactly once.
>
> Commit 04820da21050 ("staging: greybus: light: Release memory obtained by
> kasprintf") fixed the leak for the registered normal-LED path only; this
> covers the remaining cases.
>
> Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
> Assisted-by: Claude:claude-opus-4
> Signed-off-by: Cong Nguyen <congnt264@gmail.com>

Good Catch, LGTM.
Reviewed-by: Rui Miguel Silva <rui.silva@linaro.org>

Cheers,
    RUi
> ---
> Changes in v2:
> - Add Assisted-by: tag to document AI assistance, per
>   Documentation/process/coding-assistants.rst (Greg KH).
> - No functional change.
>
>  drivers/staging/greybus/light.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
> index cab02b5da867..1ecca479b5f4 100644
> --- a/drivers/staging/greybus/light.c
> +++ b/drivers/staging/greybus/light.c
> @@ -905,8 +905,6 @@ static void __gb_lights_led_unregister(struct gb_channel *channel)
>  		return;
>  
>  	led_classdev_unregister(cdev);
> -	kfree(cdev->name);
> -	cdev->name = NULL;
>  	channel->led = NULL;
>  }
>  
> @@ -1063,6 +1061,9 @@ static int gb_lights_light_register(struct gb_light *light)
>  
>  static void gb_lights_channel_free(struct gb_channel *channel)
>  {
> +	struct led_classdev *cdev = get_channel_cdev(channel);
> +
> +	kfree(cdev->name);
>  	kfree(channel->attrs);
>  	kfree(channel->attr_group);
>  	kfree(channel->attr_groups);
> -- 
> 2.25.1