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Input: leds - fix out of bound access

PATCH In review Dmitry Torokhov 3 participants 3 messages Apr 6, 2018 – Apr 12, 2018

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Stable branch HID Input drivers
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Dmitry Torokhov

author maintainer
#0 lore raw

PATCH 1/1 Input: leds - fix out of bound access

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 <[email protected]>
Tested-by Tasos Sahanidis <[email protected]>
Cc [email protected]
Signed-off-by Dmitry Torokhov <[email protected]>
---
 drivers/input/input-leds.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
drivers/input/input-leds.c +4 -4
index 766bf26601163..5f04b2d946350 100644
@@ -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);
Signature · 5 lines
2.17.0.484.g0c8726318c-goog


-- 
Dmitry
#1 lore raw

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

Reviewed-by on v1 1/1
#2 lore raw
In reply to Dmitry Torokhov
Quoted 6 lines · 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
Quoted 7 lines

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

Reported-by Tasos Sahanidis <[email protected]>
Tested-by Tasos Sahanidis <[email protected]>
Cc [email protected]
Signed-off-by Dmitry Torokhov <[email protected]>
Reviewed-by Peter Hutterer <[email protected]>

Cheers,
Peter

Quoted 36 lines
---
 drivers/input/input-leds.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
drivers/input/input-leds.c +4 -4
index 766bf26601163..5f04b2d946350 100644
@@ -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);
Signature · 1 line
2.17.0.484.g0c8726318c-goog