[PATCH 4.4 15/36] leds: do not overflow sysfs buffer in led_trigger_show

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nathan Sullivan <nathan.sulli...@ni.com>

commit 3b9b95363c45365d606ad4bbba16acca75fdf6d3 upstream.

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.sulli...@ni.com>
Signed-off-by: Zach Brown <zach.br...@ni.com>
Signed-off-by: Jacek Anaszewski <j.anaszew...@samsung.com>
Cc: Willy Tarreau <w...@1wt.eu>
Cc: Vlastimil Babka <vba...@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/leds/led-triggers.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -88,21 +88,23 @@ ssize_t led_trigger_show(struct device *
        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);