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

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Hi Zach,

On 08/16/2016 12:20 AM, Zach Brown wrote:
From: Nathan Sullivan <nathan.sullivan@xxxxxx>

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@xxxxxx>
Signed-off-by: Zach Brown <zach.brown@xxxxxx>
---
  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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