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[PATCH] leds: do not overflow sysfs buffer in led_trigger_show

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  [PATCH] leds: do not overflow sysfs buffer in led_trigger_show Zach Brown <zach.brown@ni.com> - 2016-08-16 00:40 +0200
    Re: [PATCH] leds: do not overflow sysfs buffer in led_trigger_show Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2016-08-16 22:50 +0200

#1463231 — [PATCH] leds: do not overflow sysfs buffer in led_trigger_show

From: Nathan Sullivan <nathan.sullivan@ni.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@ni.com>
Signed-off-by: Zach Brown <zach.brown@ni.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);
-- 
2.7.4

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#1464152

Hi Zach,

On 08/16/2016 12:20 AM, Zach Brown wrote:
> From: Nathan Sullivan <nathan.sullivan@ni.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@ni.com>
> Signed-off-by: Zach Brown <zach.brown@ni.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

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