linux-kernel - Re: [PATCH v2] configfs: Fix use-after-free when accessing sd->s

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Message-ID: <20190523034956.GA10043@codeaurora.org>
Date:   Thu, 23 May 2019 09:19:56 +0530
From:   Sahitya Tummala <stummala@...eaurora.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Junxiao Bi <junxiao.bi@...cle.com>,
        Joel Becker <jlbec@...lplan.org>,
        Al Viro <viro@...iv.linux.org.uk>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] configfs: Fix use-after-free when accessing
 sd->s_dentry

On Fri, May 17, 2019 at 10:23:12AM +0200, Christoph Hellwig wrote:
> On Thu, May 16, 2019 at 06:27:53PM +0530, stummala@...eaurora.org wrote:
> > Hi Christoph, Al,
> >
> > Can you please consider this patch for merging?
> 
> I've been sitting on this for a while, mostly because I can't convince
> myself it is safe.  What protects other threads from using ->s_dentry
> just when we clear it?  Also why would sd->s_dentry == dentry ever be
> false?

Thanks Christoph for getting back on this.
I will try to find answers to your queries and get back on this.

Besides, Al Viro reviewed this patch [1] and commented that fix looks
good. Hence, I was following up to get this merged as I thought it
must be a miss to not pick it up :)

[1] - https://lkml.org/lkml/2019/1/3/47

Thanks,
Sahitya.

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