linux-kernel - Re: [PATCH 1/1] Revert "iomap: fall back to buffered writes for invalidation failures"

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Message-ID: <YgPk9HhIeFM43b/a@google.com>
Date:   Wed, 9 Feb 2022 15:59:48 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Christoph Hellwig <hch@....de>
Cc:     linux-kernel@...r.kernel.org, Stable <stable@...r.kernel.org>,
        Dave Chinner <dchinner@...hat.com>,
        Goldwyn Rodrigues <rgoldwyn@...e.com>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Bob Peterson <rpeterso@...hat.com>,
        Damien Le Moal <damien.lemoal@....com>,
        Theodore Ts'o <tytso@....edu>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Ritesh Harjani <riteshh@...ux.ibm.com>,
        Johannes Thumshirn <jth@...nel.org>, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        cluster-devel@...hat.com,
        syzbot+0ed9f769264276638893@...kaller.appspotmail.com
Subject: Re: [PATCH 1/1] Revert "iomap: fall back to buffered writes for
 invalidation failures"

On Wed, 09 Feb 2022, Christoph Hellwig wrote:

> On Wed, Feb 09, 2022 at 08:52:43AM +0000, Lee Jones wrote:
> > This reverts commit 60263d5889e6dc5987dc51b801be4955ff2e4aa7.
> > 
> > Reverting since this commit opens a potential avenue for abuse.
> > 
> > The C-reproducer and more information can be found at the link below.
> > 
> > With this patch applied, I can no longer get the repro to trigger.
> 
> Well, maybe you should actually debug and try to understand what is
> going on before blindly reverting random commits.

That is not a reasonable suggestion.

Requesting that someone becomes an area expert on a huge and complex
subject such as file systems (various) in order to fix your broken
code is not rational.

If you'd like to use the PoC provided as a basis to test your own
solution, then go right ahead.  However, as it stands this API should
be considered to contain security risk and should be patched as
quickly as can be mustered.  Reversion of the offending commit seems
to be the fastest method to achieve that currently.

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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