[PATCH] Input: leds - fix out of bound access

[PATCH] Input: leds - fix out of bound access

[Dmitry Torokhov]

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

diff --git a/drivers/input/input-leds.c b/drivers/input/input-leds.c
index 766bf26601163..5f04b2d946350 100644
--- a/drivers/input/input-leds.c
+++ b/drivers/input/input-leds.c
@@ -88,6 +88,7 @@ static int input_leds_connect(struct input_handler *handler,
 			      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 input_handler *handler,
 
 	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);
-- 
2.17.0.484.g0c8726318c-goog


-- 
Dmitry

Re: [PATCH] Input: leds - fix out of bound access

[Sasha Levin]

Hi,

[This is an automated email]

This commit has been processed because it contains a -stable tag.
The stable tag indicates that it's relevant for the following trees: all

The bot has also determined it's probably a bug fixing patch. (score: 97.7389)

The bot has tested the following trees: v4.16.1, v4.15.16, v4.14.33, v4.9.93, v4.4.127.

v4.16.1: Build OK!
v4.15.16: Build OK!
v4.14.33: Build OK!
v4.9.93: Build OK!
v4.4.127: Build OK!

Please let us know if you'd like to have this patch included in a stable tree.

--
Thanks,
Sasha

Re: [PATCH] Input: leds - fix out of bound access

[Peter Hutterer]

On Fri, Apr 06, 2018 at 11:12:42AM -0700, Dmitry Torokhov wrote:
> 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>

Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>

Cheers,
   Peter

> ---
>  drivers/input/input-leds.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/input/input-leds.c b/drivers/input/input-leds.c
> index 766bf26601163..5f04b2d946350 100644
> --- a/drivers/input/input-leds.c
> +++ b/drivers/input/input-leds.c
> @@ -88,6 +88,7 @@ static int input_leds_connect(struct input_handler *handler,
>  			      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 input_handler *handler,
>  
>  	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);
> -- 
> 2.17.0.484.g0c8726318c-goog