[PATCH v4 5/5] HID: asus: use spinlock to safely schedule workers

[Pietro Borrello]

Use spinlocks to deal with workers introducing a wrapper
asus_schedule_work(), and several spinlock checks.
Otherwise, asus_kbd_backlight_set() may schedule led->work after the
structure has been freed, causing a use-after-free.

Fixes: af22a610bc38 ("HID: asus: support backlight on USB keyboards")
Signed-off-by: Pietro Borrello <borrello@xxxxxxxxxxxxxxxx>
---
 drivers/hid/hid-asus.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 9f767baf39fb..d1094bb1aa42 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -491,6 +491,16 @@ static int rog_nkey_led_init(struct hid_device *hdev)
 	return ret;
 }
 
+static void asus_schedule_work(struct asus_kbd_leds *led)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&led->lock, flags);
+	if (!led->removed)
+		schedule_work(&led->work);
+	spin_unlock_irqrestore(&led->lock, flags);
+}
+
 static void asus_kbd_backlight_set(struct led_classdev *led_cdev,
 				   enum led_brightness brightness)
 {
@@ -502,7 +512,7 @@ static void asus_kbd_backlight_set(struct led_classdev *led_cdev,
 	led->brightness = brightness;
 	spin_unlock_irqrestore(&led->lock, flags);
 
-	schedule_work(&led->work);
+	asus_schedule_work(led);
 }
 
 static enum led_brightness asus_kbd_backlight_get(struct led_classdev *led_cdev)
@@ -526,9 +536,6 @@ static void asus_kbd_backlight_work(struct work_struct *work)
 	int ret;
 	unsigned long flags;
 
-	if (led->removed)
-		return;
-
 	spin_lock_irqsave(&led->lock, flags);
 	buf[4] = led->brightness;
 	spin_unlock_irqrestore(&led->lock, flags);

-- 
2.25.1