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From: Sasha Levin <sasha.levin@oracle.com>
To: Paolo Bonzini <pbonzini@redhat.com>, Dmitry Vyukov <dvyukov@google.com>
Cc: Sasha Levin <levinsasha928@gmail.com>,
	Pekka Enberg <penberg@kernel.org>,
	Asias He <asias.hejun@gmail.com>,
	penberg@cs.helsinki.fi, Cyrill Gorcunov <gorcunov@gmail.com>,
	Will Deacon <will.deacon@arm.com>,
	andre.przywara@arm.com, matt@ozlabs.org, laijs@cn.fujitsu.com,
	Michael Ellerman <michael@ellerman.id.au>,
	Prasad Joshi <prasadjoshi124@gmail.com>,
	marc.zyngier@arm.com,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	mingo@elte.hu, gorcunov@openvz.org,
	andreas.herrmann@caviumnetworks.com, kvm@vger.kernel.org,
	Kostya Serebryany <kcc@google.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Alexey Samsonov <samsonov@google.com>,
	Alexander Potapenko <glider@google.com>
Subject: Re: sanitizing kvmtool
Date: Sun, 25 Oct 2015 15:06:44 -0400	[thread overview]
Message-ID: <562D2844.1090106@oracle.com> (raw)
In-Reply-To: <562CF2FE.3070308@redhat.com>

On 10/25/2015 11:19 AM, Paolo Bonzini wrote:
> 
> 
> On 21/10/2015 19:07, Sasha Levin wrote:
>> On 10/19/2015 11:15 AM, Dmitry Vyukov wrote:
>>> But still: if result of a racy read is passed to guest, that can leak
>>> arbitrary host data into guest.
>>
>> I see what you're saying.
> 
> I don't... how can it leak arbitrary host data?  The memcpy cannot write
> out of bounds.

The issue I had in mind (simplified) is:

vcpu1				vcpu2
----------------------------------------
guest writes idx
check if idx is valid
				guest writes new idx
access (guest mem + idx)


So I'm not sure if cover both the locking, and potential compiler tricks
sufficiently enough to prevent that scenario.


Thanks,
Sasha

      reply	other threads:[~2015-10-25 19:13 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CACT4Y+ZX71GiGzDrk4hSYVrWdoZ1eoPBdUYR_z4jY-mgOCZCuA@mail.gmail.com>
2015-10-15 10:23 ` sanitizing kvmtool Dmitry Vyukov
2015-10-17 14:16 ` Sasha Levin
2015-10-19  8:37   ` Dmitry Vyukov
2015-10-19 14:19     ` Sasha Levin
2015-10-19 14:24       ` Dmitry Vyukov
2015-10-19 14:35         ` Sasha Levin
2015-10-19 14:47           ` Dmitry Vyukov
2015-10-19 15:08             ` Sasha Levin
2015-10-19 15:15               ` Dmitry Vyukov
2015-10-21 17:07                 ` Sasha Levin
2015-10-25  9:13                   ` Dmitry Vyukov
2015-10-25 15:19                   ` Paolo Bonzini
2015-10-25 19:06                     ` Sasha Levin [this message]

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