From: Paul Durrant <Paul.Durrant@citrix.com>
To: Julien Grall <julien.grall@arm.com>,
"boris.ostrovsky@oracle.com" <boris.ostrovsky@oracle.com>,
David Vrabel <david.vrabel@citrix.com>,
"jgross@suse.com" <jgross@suse.com>,
"sstabellini@kernel.org" <sstabellini@kernel.org>,
"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>
Cc: "steve.capper@arm.com" <steve.capper@arm.com>,
Andrew Cooper <Andrew.Cooper3@citrix.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
"JBeulich@suse.com" <JBeulich@suse.com>
Subject: RE: [Xen-devel] [PATCH] xen: grant-table: Check truncation when giving access to a frame
Date: Mon, 13 Jun 2016 12:12:49 +0000 [thread overview]
Message-ID: <f840483492114a56b4bada9d3367aa76@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <1465815046-5390-1-git-send-email-julien.grall@arm.com>
> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@lists.xen.org] On Behalf Of
> Julien Grall
> Sent: 13 June 2016 11:51
> To: boris.ostrovsky@oracle.com; David Vrabel; jgross@suse.com;
> sstabellini@kernel.org; konrad.wilk@oracle.com
> Cc: steve.capper@arm.com; Andrew Cooper; linux-kernel@vger.kernel.org;
> xen-devel@lists.xen.org; Julien Grall; JBeulich@suse.com
> Subject: [Xen-devel] [PATCH] xen: grant-table: Check truncation when giving
> access to a frame
>
> The version 1 of the grant-table protocol only supports frame encoded on
> 32-bit.
>
> When the platform is supporting 48-bit physical address, the frame will
> be encoded on 36-bit which will lead a truncation and give access to
> the wrong frame.
>
> On ARM Xen will always allow the guest to use all the physical address,
> although today the RAM is always located under 40-bits (see
> xen/include/public/arch-arm.h).
>
> Add a truncation check in gnttab_update_entry_v1 to prevent the guest to
> give access to the wrong frame.
>
> Signed-off-by: Julien Grall <julien.grall@arm.com>
>
> ---
> This is limiting us to a 44-bit address space whilst ARM can support
> up to 48-bit today. This number of bit will increase to 52-bit in
> upcoming processors [1].
>
> It might be good to start thinking to extend the version 1 of the
> protocol to use 64-bit frame number.
...or simply use version 2 of the protocol.
Paul
next prev parent reply other threads:[~2016-06-13 12:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-13 10:50 [PATCH] xen: grant-table: Check truncation when giving access to a frame Julien Grall
2016-06-13 10:57 ` [Xen-devel] " David Vrabel
2016-06-13 11:10 ` Julien Grall
2016-06-13 12:20 ` Paul Durrant
2016-06-13 12:12 ` Paul Durrant [this message]
2016-06-13 12:41 ` Julien Grall
2016-06-13 12:42 ` Julien Grall
2016-06-13 12:45 ` Paul Durrant
2016-06-13 13:05 ` Julien Grall
2016-06-13 13:14 ` Paul Durrant
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