From 6bd6ae639683c0b41f46990d5c64ff9fbfa019dc Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Fri, 6 Apr 2018 10:23:05 -0700
Subject: [PATCH] Input: leds - fix out of bound access
Git-commit: 6bd6ae639683c0b41f46990d5c64ff9fbfa019dc
Patch-mainline: v4.17-rc4
References: bsc#1051510

UI_SET_LEDBIT ioctl() causes the following KASAN splat when used with
led > LED_CHARGING:

[ 1274.663418] BUG: KASAN: slab-out-of-bounds in input_leds_connect+0x611/0x730 [input_leds]
[ 1274.663426] Write of size 8 at addr ffff88003377b2c0 by task ckb-next-daemon/5128

This happens because we were writing to the led structure before making
sure that it exists.

Reported-by: Tasos Sahanidis <tasos@tasossah.com>
Tested-by: Tasos Sahanidis <tasos@tasossah.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/input/input-leds.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/input/input-leds.c
+++ b/drivers/input/input-leds.c
@@ -88,6 +88,7 @@ static int input_leds_connect(struct inp
 			      const struct input_device_id *id)
 {
 	struct input_leds *leds;
+	struct input_led *led;
 	unsigned int num_leds;
 	unsigned int led_code;
 	int led_no;
@@ -119,14 +120,13 @@ static int input_leds_connect(struct inp
 
 	led_no = 0;
 	for_each_set_bit(led_code, dev->ledbit, LED_CNT) {
-		struct input_led *led = &leds->leds[led_no];
+		if (!input_led_info[led_code].name)
+			continue;
 
+		led = &leds->leds[led_no];
 		led->handle = &leds->handle;
 		led->code = led_code;
 
-		if (!input_led_info[led_code].name)
-			continue;
-
 		led->cdev.name = kasprintf(GFP_KERNEL, "%s::%s",
 					   dev_name(&dev->dev),
 					   input_led_info[led_code].name);