linux-kernel - Re: 'WARNING in handle_exception_nmi' bug at arch/x86/kvm/vmx/vmx.c:4959

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Date:   Mon, 20 Jun 2022 13:33:23 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>,
        潘高宁 <pgn@....edu.cn>
Cc:     linux-sgx@...r.kernel.org, secalert@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        joro@...tes.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller@...glegroups.com, kangel@....edu.cn, 22121145@....edu.cn
Subject: Re: 'WARNING in handle_exception_nmi' bug at
 arch/x86/kvm/vmx/vmx.c:4959

On 6/20/22 13:24, Dmitry Vyukov wrote:
> On Mon, 20 Jun 2022 at 12:25, 潘高宁 <pgn@....edu.cn> wrote:
>>
>> Hello,
>>
>>      This is Xiao Lei, Gaoning Pan and Yongkang Jia from Zhejiang University. We found a 'WARNING in handle_exception_nmi' bug by syzkaller. This flaw allows a malicious user in a local DoS condition. The following program triggers Local DoS at arch/x86/kvm/vmx/vmx.c:4959 in latest release linux-5.18.5, this bug can be reproducible stably by the C reproducer:
> 
> 
> FWIW a similarly-looking issue was reported by syzbot:
> https://syzkaller.appspot.com/bug?id=1b411bfb1739c497a8f0c7f1aa501202726cd01a
> https://lore.kernel.org/all/0000000000000a5eae05d8947adb@google.com/
> 
> Sean said it may be an issue in L0 kernel rather than in the tested kernel:
> https://lore.kernel.org/all/Yqd5upAHNOxD0wrQ@google.com/

Indeed I cannot reproduce these either on bare metal.

Paolo