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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Mon, 28 Sep 2020 12:33:57 +0200
Message-ID: <CACT4Y+Z4Y6SJJ6iYBhVRiknrWBAD6gGhQXiXLhxPniDNBFJGsA@mail.gmail.com>
Subject: Re: general protection fault in perf_misc_flags
To:     Borislav Petkov <bp@alien8.de>
Cc:     Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        syzbot <syzbot+ce179bc99e64377c24bc@syzkaller.appspotmail.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Jiri Olsa <jolsa@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Ingo Molnar <mingo@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
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On Mon, Sep 28, 2020 at 10:54 AM Borislav Petkov <bp@alien8.de> wrote:
>
> On Mon, Sep 28, 2020 at 10:40:19AM +0200, Dmitry Vyukov wrote:
> > I meant the kernel self-corrupts itself, that just wasn't detected by
> > KASAN, page protections, etc.
>
> Well, Nick already asked this but we're marking all kernel text RO early
> during boot. So it either is happening before that or something else
> altogether is going on.
>
> And if that is a kernel issue, I believe we should've heard by now from
> others. Or maybe this happens only in VMs.
>
> Questions over questions...

I don't have answers to all of the questions, but syzkaller produces a
pretty unique workload. It has found thousands of bugs that you have
not heard from others:
https://syzkaller.appspot.com/upstream#open
https://syzkaller.appspot.com/upstream/fixed
In particular there are hundreds of known and active potential memory
corruption bugs.

It may be related to VMs, but also may well not be related to VMs.