linux-kernel - Re: [PATCH] leds: do not overflow sysfs buffer in led_trigger

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Message-ID: <57B37A1C.2070707@gmail.com>
Date:	Tue, 16 Aug 2016 22:39:56 +0200
From:	Jacek Anaszewski <jacek.anaszewski@...il.com>
To:	Zach Brown <zach.brown@...com>, rpurdie@...ys.net,
	j.anaszewski@...sung.com
Cc:	linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
	nathan.sullivan@...com
Subject: Re: [PATCH] leds: do not overflow sysfs buffer in led_trigger_show

Hi Zach,

On 08/16/2016 12:20 AM, Zach Brown wrote:
> From: Nathan Sullivan <nathan.sullivan@...com>
>
> Per the documentation, use scnprintf instead of sprintf to ensure there
> is never more than PAGE_SIZE bytes of trigger names put into the
> buffer.
>
> Signed-off-by: Nathan Sullivan <nathan.sullivan@...com>
> Signed-off-by: Zach Brown <zach.brown@...com>
> ---
>   drivers/leds/led-triggers.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
> index c92702a..8668538 100644
> --- a/drivers/leds/led-triggers.c
> +++ b/drivers/leds/led-triggers.c
> @@ -81,21 +81,23 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
>   	down_read(&led_cdev->trigger_lock);
>
>   	if (!led_cdev->trigger)
> -		len += sprintf(buf+len, "[none] ");
> +		len += scnprintf(buf+len, PAGE_SIZE - len, "[none] ");
>   	else
> -		len += sprintf(buf+len, "none ");
> +		len += scnprintf(buf+len, PAGE_SIZE - len, "none ");
>
>   	list_for_each_entry(trig, &trigger_list, next_trig) {
>   		if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
>   							trig->name))
> -			len += sprintf(buf+len, "[%s] ", trig->name);
> +			len += scnprintf(buf+len, PAGE_SIZE - len, "[%s] ",
> +					 trig->name);
>   		else
> -			len += sprintf(buf+len, "%s ", trig->name);
> +			len += scnprintf(buf+len, PAGE_SIZE - len, "%s ",
> +					 trig->name);
>   	}
>   	up_read(&led_cdev->trigger_lock);
>   	up_read(&triggers_list_lock);
>
> -	len += sprintf(len+buf, "\n");
> +	len += scnprintf(len+buf, PAGE_SIZE - len, "\n");
>   	return len;
>   }
>   EXPORT_SYMBOL_GPL(led_trigger_show);
>

Thanks for the patch, applied.

-- 
Best regards,
Jacek Anaszewski