From: Joerg Roedel <joro@8bytes.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: iommu@lists.linux-foundation.org, shawn.lin@rock-chips.com,
marc.zyngier@arm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu: Avoid NULL group dereference
Date: Thu, 17 Aug 2017 17:41:01 +0200 [thread overview]
Message-ID: <20170817154101.GL16908@8bytes.org> (raw)
In-Reply-To: <59a6c4f0a790eea40e2b2f2be840b63317dd44e4.1502966326.git.robin.murphy@arm.com>
On Thu, Aug 17, 2017 at 11:40:08AM +0100, Robin Murphy wrote:
> The recently-removed FIXME in iommu_get_domain_for_dev() turns out to
> have been a little misleading, since that check is still worthwhile even
> when groups *are* universal. We have a few IOMMU-aware drivers which
> only care whether their device is already attached to an existing domain
> or not, for which the previous behaviour of iommu_get_domain_for_dev()
> was ideal, and who now crash if their device does not have an IOMMU.
>
> With IOMMU groups now serving as a reliable indicator of whether a
> device has an IOMMU or not (barring false-positives from VFIO no-IOMMU
> mode), drivers could arguably do this:
>
> group = iommu_group_get(dev);
> if (group) {
> domain = iommu_get_domain_for_dev(dev);
> iommu_group_put(group);
> }
Okay, so just to check I got it right: Drivers do the above to check
whether a device is managed by an IOMMU, and that crashes now because
the 'group == NULL' check was removed?
Regards,
Joerg
next prev parent reply other threads:[~2017-08-17 15:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-17 10:40 [PATCH] iommu: Avoid NULL group dereference Robin Murphy
2017-08-17 10:51 ` Marc Zyngier
2017-08-17 15:41 ` Joerg Roedel [this message]
2017-08-17 16:56 ` Robin Murphy
2017-08-18 9:42 ` Joerg Roedel
2017-08-18 0:49 ` Shawn Lin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170817154101.GL16908@8bytes.org \
--to=joro@8bytes.org \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=robin.murphy@arm.com \
--cc=shawn.lin@rock-chips.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox