linux-kernel - Re: [PATCH] class: fix use-after-free in class

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Date: Mon, 18 Dec 2023 07:52:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Chunyan Zhang <chunyan.zhang@...soc.com>
Cc: "Rafael J . Wysocki" <rafael@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, Jing Xia <jing.xia@...soc.com>,
	Jing Xia <jing.xia.mail@...il.com>,
	Xuewen Yan <xuewen.yan@...soc.com>, Ke Wang <ke.wang@...soc.com>,
	Chunyan Zhang <zhang.lyra@...il.com>
Subject: Re: [PATCH] class: fix use-after-free in class_register()

On Mon, Dec 18, 2023 at 10:44:03AM +0800, Chunyan Zhang wrote:
> From: Jing Xia <jing.xia@...soc.com>
> 
> The lock_class_key is still registered and can be found in
> lock_keys_hash hlist after subsys_private is freed in error
> handler path.A task who iterate over the lock_keys_hash
> later may cause use-after-free.So fix that up and unregister
> the lock_class_key before kfree(cp).

What task iterates over all hashes?

And can you put ' ' after your '.'?

And how was this found?

> 
> Signed-off-by: Jing Xia <jing.xia@...soc.com>
> Signed-off-by: Xuewen Yan <xuewen.yan@...soc.com>

What commit id does this fix?

Also note in the changelog that this only can happen if lockdep is
enabled, which is not true for normal systems.

thanks,

greg k-h