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From:   Andrey Konovalov <andreyknvl@gmail.com>
Date:   Tue, 27 Sep 2022 18:55:23 +0200
Message-ID: <CA+fCnZcpba7qinx4DmuJPjRQj07uJ5H9Xq9Zhi8v1rw-AW_yWQ@mail.gmail.com>
Subject: Re: [syzbot] KASAN: invalid-access Read in copy_page
To:     Catalin Marinas <catalin.marinas@arm.com>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        tongtiangen@huawei.com,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Will Deacon <will@kernel.org>,
        syzbot <syzbot+c2c79c6d6eddc5262b77@syzkaller.appspotmail.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Peter Collingbourne <pcc@google.com>,
        Dmitry Vyukov <dvyukov@google.com>
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On Tue, Sep 6, 2022 at 6:23 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Tue, Sep 06, 2022 at 04:39:57PM +0200, Andrey Konovalov wrote:
> > On Tue, Sep 6, 2022 at 4:29 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > > > > Does it take long to reproduce this kasan warning?
> > > >
> > > > syzbot finds several such cases every day (200 crashes for the past 35 days):
> > > > https://syzkaller.appspot.com/bug?extid=c2c79c6d6eddc5262b77
> > > > So once it reaches the tested tree, we should have an answer within a day.
> >
> > To be specific, this syzkaller instance fuzzes the mainline, so the
> > patch with the WARN_ON needs to end up there.
> >
> > If this is unacceptable, perhaps, we could switch the MTE syzkaller
> > instance to the arm64 testing tree.
>
> It needs some more digging first. My first guess was that a PROT_MTE
> page was mapped into the user address space and the task repainted it
> but I don't think that's the case.

Hi Catalin,

syzkaller still keeps hitting this issue and I was wondering if you
have any ideas of what could be wrong here?

> Since I can't find the kernel boot log for these runs, is there any kind
> of swap enabled? I'm trying to narrow down where the problem may be.

I don't think there is.

Thanks!