[PATCH] HID: asus: fix UAF of ->kbd_backlight on !CONFIG_ASUS_WMI

[Jann Horn]

On kernels without !CONFIG_ASUS_WMI, asus_hid_register_listener() will
fail. asus_kbd_register_leds() reacts to this by freeing
drvdata->kbd_backlight, but doesn't NULL out the pointer, causing UAF when
asus_remove() follows this pointer.

I have tested that this bug causes an ASAN splat, and that this change
fixes the issue.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: af22a610bc38 ("HID: asus: support backlight on USB keyboards")
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
---
 drivers/hid/hid-asus.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 3f5e96900b67..c2a5edebbd7a 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -777,6 +777,7 @@ static int asus_kbd_register_leds(struct hid_device *hdev)
 	if (ret < 0) {
 		/* No need to have this still around */
 		devm_kfree(&hdev->dev, drvdata->kbd_backlight);
+		drvdata->kbd_backlight = NULL;
 	}
 
 	return ret;

---
base-commit: 51512e22efe813d8223de27f6fd02a8a48ea2323
change-id: 20260703-hid-asus-uaf-0b8e1325fc00

Best regards,
--  
Jann Horn <jannh@xxxxxxxxxx>