linux-kernel - Re: [PATCH] KVM: x86: Forcibly leave nested virt when SMM state is toggled

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Date:   Fri, 18 Feb 2022 19:14:28 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Tadeusz Struk <tadeusz.struk@...aro.org>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        syzbot+8112db3ab20e70d50c31@...kaller.appspotmail.com
Subject: Re: [PATCH] KVM: x86: Forcibly leave nested virt when SMM state is
 toggled

On 2/18/22 18:22, Tadeusz Struk wrote:
> On 2/18/22 08:58, Sean Christopherson wrote:
>> This SMM-specific patch fixes something different, the bug that you 
>> are still
>> hitting is the FNAME(cmpxchg_gpte) mess.  The uaccess CMPXCHG 
>> series[*] that
>> properly fixes that issue hasn't been merged yet.
>>
>>    ==================================================================
>>    BUG: KASAN: use-after-free in ept_cmpxchg_gpte.constprop.0+0x3c3/0x590
>>    Write of size 8 at addr ffff888010000000 by task repro/5633
>>
>> [*]https://lore.kernel.org/all/20220202004945.2540433-1-seanjc@google.com
>>
> 
> Ok, that's good. I will keep an eye on it and give it a try then.

I'll poke PeterZ for a review next week.

Paolo