ALSA: ac97: fix a double free in snd_ac97_controller_register()

If ac97_add_adapter() fails, put_device() is the correct way to drop
the device reference. kfree() is not required.
Add kfree() if idr_alloc() fails and in ac97_adapter_release() to do
the cleanup.

Found by code review.

Fixes: 74426fb ("ALSA: ac97: add an ac97 bus")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Link: https://patch.msgid.link/20251219162845.657525-1-lihaoxiang@isrc.iscas.ac.cn
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Author: Haoxiang Li

sound/ac97/bus.c

@@ -298,6 +298,7 @@ static void ac97_adapter_release(struct device *dev)
 	idr_remove(&ac97_adapter_idr, ac97_ctrl->nr);
 	dev_dbg(&ac97_ctrl->adap, "adapter unregistered by %s\n",
 		dev_name(ac97_ctrl->parent));
+	kfree(ac97_ctrl);
 }
 
 static const struct device_type ac97_adapter_type = {
@@ -319,7 +320,9 @@ static int ac97_add_adapter(struct ac97_controller *ac97_ctrl)
 		ret = device_register(&ac97_ctrl->adap);
 		if (ret)
 			put_device(&ac97_ctrl->adap);
-	}
+	} else
+		kfree(ac97_ctrl);
+
 	if (!ret) {
 		list_add(&ac97_ctrl->controllers, &ac97_controllers);
 		dev_dbg(&ac97_ctrl->adap, "adapter registered by %s\n",
@@ -361,14 +364,11 @@ struct ac97_controller *snd_ac97_controller_register(
 	ret = ac97_add_adapter(ac97_ctrl);
 
 	if (ret)
-		goto err;
+		return ERR_PTR(ret);
 	ac97_bus_reset(ac97_ctrl);
 	ac97_bus_scan(ac97_ctrl);
 
 	return ac97_ctrl;
-err:
-	kfree(ac97_ctrl);
-	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(snd_ac97_controller_register);