FAILED: patch "[PATCH] ALSA: ac97: fix a double free in" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 830988b6cf197e6dcffdfe2008c5738e6c6c3c0f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026011239-handled-worried-ca90@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 830988b6cf197e6dcffdfe2008c5738e6c6c3c0f Mon Sep 17 00:00:00 2001
From: Haoxiang Li <[email protected]>
Date: Sat, 20 Dec 2025 00:28:45 +0800
Subject: [PATCH] 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.

index f4254703d29f..bb9b795e0226 100644
@@ -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);