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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Jacek Anaszewski" <j.anaszewski@samsung.com>,
        "Zach Brown" <zach.brown@ni.com>,
        "Vlastimil Babka" <vbabka@suse.cz>,
        "Nathan Sullivan" <nathan.sullivan@ni.com>
Date:   Sun, 11 Nov 2018 19:49:05 +0000
Message-ID: <lsq.1541965745.55345034@decadent.org.uk>
Subject: [PATCH 3.16 331/366] leds: do not overflow sysfs buffer in
 led_trigger_show
In-Reply-To: <lsq.1541965744.387173642@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

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

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);