From: David Marchand <david.marchand@redhat.com>
To: "Burakov, Anatoly" <anatoly.burakov@intel.com>,
"Ding, Xuan" <xuan.ding@intel.com>
Cc: dev <dev@dpdk.org>, Maxime Coquelin <maxime.coquelin@redhat.com>
Subject: Re: [dpdk-dev] [PATCH v1 1/1] vfio: fix partial unmap check
Date: Thu, 28 Oct 2021 09:52:57 +0200 [thread overview]
Message-ID: <CAJFAV8xsb5NnK4Adbfup9rfiF3HC_vfeV39ndTN_HLuXseOrJQ@mail.gmail.com> (raw)
In-Reply-To: <BN9PR11MB551388F77C6EC758447FF3F4E7869@BN9PR11MB5513.namprd11.prod.outlook.com>
On Thu, Oct 28, 2021 at 8:06 AM Ding, Xuan <xuan.ding@intel.com> wrote:
> >> Partial unmap support was introduced in commit c13ca4e81cac, and with it
> >> was added a check that dereferenced the IOMMU type to determine
> >whether
> >> partial ummapping is supported for currently configured IOMMU type. In
> >> certain circumstances (such as when VFIO is supported, but no devices
> >> were bound to the VFIO driver), the IOMMU type pointer can be NULL.
> >>
> >> However, dereferencing of IOMMU type was guarded by access to the user
> >> maps list - that is, we were always checking the user map list first,
> >> and then, if we found a memory region that encloses the one we're trying
> >> to unmap, we would have performed the IOMMU type check.
> >>
> >> This ensured that the IOMMU type check will not cause any NULL pointer
> >> dereferences, because in order for an IOMMU type check to have been
> >> performed, there necessarily must have been at least one memory region
> >> that was previously mapped successfully, and that implies having a
> >> defined IOMMU type.
> >>
> >> When 56259f7fc010 was introduced, the IOMMU type check was moved to
> >> before we were traversing the user mem maps list, thereby introducing a
> >> potential NULL dereference, because the IOMMU type access was no longer
> >> guarded by the user mem maps list traversal.
> >>
> >> Fix the issue by moving the IOMMU type check to after the user mem maps
> >> traversal, thereby ensuring that by the time the check happens, the
> >> IOMMU type is always valid.
> >>
> >> Fixes: 56259f7fc010 ("vfio: allow partially unmapping adjacent memory")
> >> Cc: xuan.ding@intel.com
> >>
> >> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> >Reviewed-by: David Marchand <david.marchand@redhat.com>
> Tested-by: Xuan Ding <xuan.ding@intel.com>
Applied, thanks.
--
David Marchand
prev parent reply other threads:[~2021-10-28 7:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 13:26 Anatoly Burakov
2021-10-27 14:49 ` David Marchand
2021-10-28 6:05 ` Ding, Xuan
2021-10-28 7:52 ` David Marchand [this message]
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=CAJFAV8xsb5NnK4Adbfup9rfiF3HC_vfeV39ndTN_HLuXseOrJQ@mail.gmail.com \
--to=david.marchand@redhat.com \
--cc=anatoly.burakov@intel.com \
--cc=dev@dpdk.org \
--cc=maxime.coquelin@redhat.com \
--cc=xuan.ding@intel.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;
as well as URLs for NNTP newsgroup(s).