linux-kernel - Re: [PATCH v2] kernfs: fix use-after-free in __kernfs

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Message-ID: <YyioZk1fLVFZHWwn@slm.duckdns.org>
Date:   Mon, 19 Sep 2022 07:35:34 -1000
From:   Tejun Heo <tj@...nel.org>
To:     "Christian A. Ehrhardt" <lk@...e.de>
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v2] kernfs: fix use-after-free in __kernfs_remove

On Tue, Sep 13, 2022 at 02:17:23PM +0200, Christian A. Ehrhardt wrote:
> Syzkaller managed to trigger concurrent calls to
> kernfs_remove_by_name_ns() for the same file resulting in
> a KASAN detected use-after-free. The race occurs when the root
> node is freed during kernfs_drain().
> 
> To prevent this acquire an additional reference for the root
> of the tree that is removed before calling __kernfs_remove().
...
> cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> cc: Tejun Heo <tj@...nel.org>
> Signed-off-by: Christian A. Ehrhardt <lk@...e.de>

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun