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Date: Mon, 6 May 2024 17:30:59 -0700
From: Luis Chamberlain <mcgrof@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: ziy@nvidia.com, linux-mm@kvack.org, fstests@vger.kernel.org,
	linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	willy@infradead.org, hare@suse.de, john.g.garry@oracle.com,
	p.raghav@samsung.com, da.gomez@samsung.com
Subject: Re: [PATCH 1/2] mm/huge_memory: skip invalid debugfs file entry for
 folio split
Message-ID: <Zjl2Q5fjudt75uvk@bombadil.infradead.org>
References: <20240424225449.1498244-1-mcgrof@kernel.org>
 <20240424225449.1498244-2-mcgrof@kernel.org>
 <20240425140126.2a62a5ec686813ee7deea658@linux-foundation.org>
 <Zi8cYrtxyO7Uw-Mc@bombadil.infradead.org>
 <20240429092307.37bf51c79f70bad4922f6277@linux-foundation.org>
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Sender: Luis Chamberlain <mcgrof@infradead.org>

On Mon, Apr 29, 2024 at 09:23:07AM -0700, Andrew Morton wrote:
> On Sun, 28 Apr 2024 21:04:50 -0700 Luis Chamberlain <mcgrof@kernel.org> wrote:
> 
> > On Thu, Apr 25, 2024 at 02:01:26PM -0700, Andrew Morton wrote:
> > > On Wed, 24 Apr 2024 15:54:48 -0700 Luis Chamberlain <mcgrof@kernel.org> wrote:
> > > 
> > > > If the file entry is too long we may easily end up going out of bounds
> > > > and crash after strsep() on sscanf(). 
> > > > 
> > > 
> > > Can you explain why?  I'm not seeing it.
> > 
> > I couldn't see it either but I just looked at the crash below and
> > its the only thing I could think of. So I think its when userspace
> > somehow abuses MAX_INPUT_BUF_SZ a lot somehow.
> 
> This isn't a good basis for making kernel changes :(
> 
> Can you investigate a little further please?

Sure, this will require some more time, feel free to ignore these two
patches for now then.

  Luis