[PATCH v3 4/8] HID: asus: cleanup keyboard listener on failure: avoid use-after-free

[Denis Benato <denis.benato@linux.dev>]

asus_kbd_register_leds(), I noticed it registers a listener to a global list
and uses devm_kzalloc(). If a subsequent initialization step in asus_probe()
fails the driver returns without unregistering the listener, and the devres
subsystem will automatically free the memory, leaving a dangling pointer
in the global list.

Fixes: b34b5945a769 ("HID: asus: listen to the asus-wmi brightness device instead of creating one")
Reported-by: sahiko-bot@kernel.org
Signed-off-by: Denis Benato <denis.benato@linux.dev>
---
 drivers/hid/hid-asus.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 0a6c97155549..f38b18ad65c6 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -1426,11 +1426,17 @@ static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		if (drvdata->tp) {
 			ret = asus_start_multitouch(hdev);
 			if (ret)
-				goto err_stop_hw;
+				goto err_unregister_backlight;
 		}
 	}
 
 	return 0;
+err_unregister_backlight:
+	if (drvdata->kbd_backlight) {
+		asus_hid_unregister_listener(&drvdata->kbd_backlight->listener);
+		devm_kfree(&hdev->dev, drvdata->kbd_backlight);
+		drvdata->kbd_backlight = NULL;
+	}
 err_stop_hw:
 	hid_hw_stop(hdev);
 	return ret;
-- 
2.47.3