From: Peter Xu <peterx@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
eric.auger@redhat.com, cohuck@redhat.com
Subject: Re: [PATCH v2] vfio/type1: Limit DMA mappings per container
Date: Wed, 3 Apr 2019 14:05:58 +0800 [thread overview]
Message-ID: <20190403060558.GL11008@xz-x1> (raw)
In-Reply-To: <155422160029.16896.1992475589398080933.stgit@gimli.home>
On Tue, Apr 02, 2019 at 10:15:38AM -0600, Alex Williamson wrote:
> Memory backed DMA mappings are accounted against a user's locked
> memory limit, including multiple mappings of the same memory. This
> accounting bounds the number of such mappings that a user can create.
> However, DMA mappings that are not backed by memory, such as DMA
> mappings of device MMIO via mmaps, do not make use of page pinning
> and therefore do not count against the user's locked memory limit.
> These mappings still consume memory, but the memory is not well
> associated to the process for the purpose of oom killing a task.
>
> To add bounding on this use case, we introduce a limit to the total
> number of concurrent DMA mappings that a user is allowed to create.
> This limit is exposed as a tunable module option where the default
> value of 64K is expected to be well in excess of any reasonable use
> case (a large virtual machine configuration would typically only make
> use of tens of concurrent mappings).
>
> This fixes CVE-2019-3882.
>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2019-04-03 6:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-02 16:15 [PATCH v2] vfio/type1: Limit DMA mappings per container Alex Williamson
2019-04-02 19:14 ` Auger Eric
2019-04-03 6:05 ` Peter Xu [this message]
2019-04-03 7:18 ` Cornelia Huck
2019-04-03 19:24 ` Jerome Glisse
2019-04-03 20:00 ` Alex Williamson
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