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Re: [Xen-ia64-devel] [PATCH][TAKE3] Fix vulnerability of copy_to_user in

To: Alex Williamson <alex.williamson@xxxxxx>
Subject: Re: [Xen-ia64-devel] [PATCH][TAKE3] Fix vulnerability of copy_to_user in PAL emulation
From: Jarod Wilson <jwilson@xxxxxxxxxx>
Date: Fri, 14 Dec 2007 13:55:33 -0500
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Alex Williamson wrote:
On Fri, 2007-12-14 at 15:52 +0900, Kouya Shimura wrote:
Hi,

The reputation of my previous patch was not so good,
then I rewrote it. An attached patch is temporary fix
for xen-3.2.

Anyone know offhand if this vulnerability exists in xen 3.1.x as well? (As in, is this something a certain vendor shipping a xen 3.1.x codebase needs to pull into their own tree ASAP? :)


I think this patch is enough for normal usage.
Please see SDM Vol2 11.10.2.1.3 "Making PAL Procedure Calls in Physical or Virtual Mode".
If the caller has a responsibility of providing DTR or DTC
mapping, xencomm for PAL might be unnecessary. I confirmed there is no problem in linux, windows 2003, windows 2008 with this patch.

As for PV domain, the same logic can't be used due to only one vTLB. This patch only checks that the buffer
never point VMM address, that would avoid the vulnerability.

   Thanks for fixing this.  Applied.  Thanks,

--
Jarod Wilson
jwilson@xxxxxxxxxx


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