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Date:   Tue, 3 Sep 2019 09:14:46 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Christoph Hellwig <hch@lst.de>
Cc:     linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
        Goldwyn Rodrigues <rgoldwyn@suse.de>,
        Matthew Bobrowski <mbobrowski@mbobrowski.org>
Subject: Re: [PATCH 2/2] iomap: move the iomap_dio_rw ->end_io callback into
 a structure
Message-ID: <20190903161446.GH29434@bombadil.infradead.org>
References: <20190903130327.6023-1-hch@lst.de>
 <20190903130327.6023-3-hch@lst.de>
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On Tue, Sep 03, 2019 at 03:03:27PM +0200, Christoph Hellwig wrote:
> Add a new iomap_dio_ops structure that for now just contains the end_io
> handler.  This avoid storing the function pointer in a mutable structure,
> which is a possible exploit vector for kernel code execution, and prepares
> for adding a submit_io handler that btrfs needs.

Is it really a security win?  If I can overwrite dio->end_io, I can as
well overwrite dio->dops.

The patch itself looks sane, but I'm not sure about this particular reason.