From: Christoph Hellwig <hch@lst.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>,
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
Date: Wed, 4 Sep 2019 14:51:10 +0200 [thread overview]
Message-ID: <20190904125110.GB17285@lst.de> (raw)
In-Reply-To: <20190903161446.GH29434@bombadil.infradead.org>
On Tue, Sep 03, 2019 at 09:14:46AM -0700, Matthew Wilcox wrote:
> 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.
Which you'd then need to point to another place where you can stuff
function pointer. Not impossible, but just another hoop to jump
through. At least until we add run-time checks that ops structures
are in read-only memory, which sounds more sensible than some of the
other security hardening patches floating around.
next prev parent reply other threads:[~2019-09-04 12:51 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-03 13:03 iomap_dio_rw ->end_io improvements Christoph Hellwig
2019-09-03 13:03 ` [PATCH 1/2] iomap: split size and error for iomap_dio_rw ->end_io Christoph Hellwig
2019-09-03 14:44 ` Darrick J. Wong
2019-09-03 15:24 ` Matthew Wilcox
2019-09-03 13:03 ` [PATCH 2/2] iomap: move the iomap_dio_rw ->end_io callback into a structure Christoph Hellwig
2019-09-03 14:46 ` Darrick J. Wong
2019-09-03 16:14 ` Matthew Wilcox
2019-09-04 12:51 ` Christoph Hellwig [this message]
2019-09-03 21:32 ` iomap_dio_rw ->end_io improvements Matthew Bobrowski
2019-09-03 22:16 ` Darrick J. Wong
2019-09-04 2:19 ` Damien Le Moal
2019-09-04 5:12 ` Christoph Hellwig
2019-09-04 11:46 ` Andreas Gruenbacher
2019-09-04 17:45 ` Darrick J. Wong
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