[PATCH 3.16 331/366] leds: do not overflow sysfs buffer in led_trigger_show

Ben Hutchings
2018-11-11T20:28:14Z

From: Nathan Sullivan <nathan.sullivan@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.sullivan@ni.com>
Signed-off-by: Zach Brown <zach.brown@ni.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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
@@ -78,21 +78,23 @@ 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);