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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Wed, 24 Feb 2021 18:12:57 +0100
Message-ID: <CACT4Y+ZaGOpJ1+dxfTVWhNuV5hFJmx=HgPqVf6bqWE==7PeFFQ@mail.gmail.com>
Subject: Re: general protection fault in vmx_vcpu_run (2)
To:     Borislav Petkov <bp@alien8.de>
Cc:     syzbot <syzbot+42a71c84ef04577f1aef@syzkaller.appspotmail.com>,
        Dave Hansen <dave.hansen@intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        KVM list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Ingo Molnar <mingo@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>, seanjc@google.com,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vitaly Kuznetsov <vkuznets@redhat.com>, wanpengli@tencent.com,
        "the arch/x86 maintainers" <x86@kernel.org>
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On Wed, Feb 24, 2021 at 1:27 PM Borislav Petkov <bp@alien8.de> wrote:
>
> On Tue, Feb 23, 2021 at 03:17:07PM -0800, syzbot wrote:
> > syzbot has bisected this issue to:
> >
> > commit 167dcfc08b0b1f964ea95d410aa496fd78adf475
> > Author: Lorenzo Stoakes <lstoakes@gmail.com>
> > Date:   Tue Dec 15 20:56:41 2020 +0000
> >
> >     x86/mm: Increase pgt_buf size for 5-level page tables
> >
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13fe3ea8d00000
> > start commit:   a99163e9 Merge tag 'devicetree-for-5.12' of git://git.kern..
> > git tree:       upstream
> > final oops:     https://syzkaller.appspot.com/x/report.txt?x=10013ea8d00000
>
> No oops here.
>
> > console output: https://syzkaller.appspot.com/x/log.txt?x=17fe3ea8d00000
>
> Nothing special here too.
>
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=49116074dd53b631
>
> Tried this on two boxes, the Intel one doesn't even boot with that
> config - and it is pretty standard one - and on the AMD one the
> reproducer doesn't trigger anything. It probably won't because the GP
> is in vmx_vcpu_run() but since the ioctls were doing something with
> IRQCHIP, I thought it is probably vendor-agnostic.
>
> So, all in all, I could use some more info on how you're reproducing and
> maybe you could show the oops too.

Hi Boris,

Looking at the bisection log, the bisection was distracted by something else.
You can always find the original reported issue over the dashboard link:
https://syzkaller.appspot.com/bug?extid=42a71c84ef04577f1aef
or on lore:
https://lore.kernel.org/lkml/0000000000007ff56205ba985b60@google.com/