Re: [PATCH 14/21] leds: flash: Avoid divide-by-zero in led_clamp_align()

[David Laight]

On Wed, 21 Oct 2026 12:32:23 +0000
Lee Jones <lee@xxxxxxxxxx> wrote:

> If a flash LED driver leaves a setting's step size as zero, writing to
> the corresponding sysfs attribute invokes led_clamp_align() and triggers
> an integer division by zero when aligning the offset to s->step.
> 
> Clamp s->val to [s->min, s->max] and return early when s->step is zero.
> 
> Fixes: 7aea8389a77a ("leds: Add LED Flash class extension to the LED subsystem")
> Closes: https://sashiko.dev/#/bug/linux-9d06d7fe-310b-4aee-8b16-0fb49550c287
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
> ---
>  drivers/leds/led-class-flash.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
> index 181dfd49c6ad..16b3b6b9365b 100644
> --- a/drivers/leds/led-class-flash.c
> +++ b/drivers/leds/led-class-flash.c
> @@ -375,6 +375,11 @@ static void led_clamp_align(struct led_flash_setting *s)
>  {
>  	u32 v, offset;
>  
> +	if (!s->step) {
> +		s->val = clamp(s->val, s->min, s->max);
> +		return;
> +	}

Why not just:
	u32 step = s->step ?: 1;
and then use step instead of s->step.

David

> +
>  	v = s->val + s->step / 2;
>  	v = clamp(v, s->min, s->max);
>  	offset = v - s->min;