linux-kernel - Re: [PATCH 2/2] KVM: s390: Return last valid slot if approx index is out-of-bounds

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Message-ID: <40b325c7-ca24-3513-b2fa-1e9397c9e353@redhat.com>
Date:   Wed, 8 Apr 2020 13:33:52 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        syzbot+d889b59b2bb87d4047a2@...kaller.appspotmail.com
Subject: Re: [PATCH 2/2] KVM: s390: Return last valid slot if approx index is
 out-of-bounds

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@...ux.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?

Thanks,

Paolo