From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Janosch Frank <frankja@linux.ibm.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+d889b59b2bb87d4047a2@syzkaller.appspotmail.com
Subject: Re: [PATCH 2/2] KVM: s390: Return last valid slot if approx index is out-of-bounds
Date: Wed, 8 Apr 2020 13:40:09 +0200 [thread overview]
Message-ID: <875ba09c-eb1b-1cdd-f198-0bfbdb607d4b@de.ibm.com> (raw)
In-Reply-To: <40b325c7-ca24-3513-b2fa-1e9397c9e353@redhat.com>
On 08.04.20 13:33, Paolo Bonzini wrote:
> On 08/04/20 12:21, Claudio Imbrenda wrote:
>> on s390 memory always starts at 0; you can't even boot a system missing
>> the first pages of physical memory, so this means this situation would
>> never happen in practice.
>>
>> of course, a malicious userspace program could create an (unbootable) VM
>> and trigger this bug, so the patch itself makes sense.
>>
>> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
>
> What about using KVM just for isolation and not just to run a full-blown
> OS (that is, you might even only have the guest run in problem state)?
> Would that be feasible on s390?
You always need 2 prefix pages. Otherwise the SIE instruction refuses to start.
By default this starts as address 0. You might be also to set the prefix register
to something else adn then this could maybe work.
next prev parent reply other threads:[~2020-04-08 11:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-08 6:40 [PATCH 0/2] KVM: Fix out-of-bounds memslot access Sean Christopherson
2020-04-08 6:40 ` [PATCH 1/2] KVM: Check validity of resolved slot when searching memslots Sean Christopherson
2020-04-08 7:04 ` Cornelia Huck
2020-04-08 6:40 ` [PATCH 2/2] KVM: s390: Return last valid slot if approx index is out-of-bounds Sean Christopherson
2020-04-08 7:10 ` Cornelia Huck
2020-04-08 9:08 ` Paolo Bonzini
2020-04-08 7:28 ` Christian Borntraeger
2020-04-08 10:21 ` Claudio Imbrenda
2020-04-08 11:33 ` Paolo Bonzini
2020-04-08 11:40 ` Christian Borntraeger [this message]
2020-04-08 6:55 ` [PATCH 0/2] KVM: Fix out-of-bounds memslot access Christian Borntraeger
2020-04-08 7:24 ` Christian Borntraeger
2020-04-08 8:10 ` Cornelia Huck
2020-04-08 14:23 ` Sean Christopherson
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