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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Sun, 22 Mar 2020 14:43:40 +0100
Message-ID: <CACT4Y+YGjaD4dobFgB7ieVi3wbG72_EPdXuJQ+h4qQq1Qncspg@mail.gmail.com>
Subject: Re: BUG: unable to handle kernel NULL pointer dereference in handle_external_interrupt_irqoff
To:     syzbot <syzbot+3f29ca2efb056a761e38@syzkaller.appspotmail.com>
Cc:     Borislav Petkov <bp@alien8.de>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        David Miller <davem@davemloft.net>,
        David Howells <dhowells@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kuba@kernel.org,
        KVM list <kvm@vger.kernel.org>, linux-afs@lists.infradead.org,
        LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        netdev <netdev@vger.kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        "Christopherson, Sean J" <sean.j.christopherson@intel.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 Sun, Mar 22, 2020 at 2:29 PM syzbot
<syzbot+3f29ca2efb056a761e38@syzkaller.appspotmail.com> wrote:
>
> syzbot has bisected this bug to:
>
> commit f71dbf2fb28489a79bde0dca1c8adfb9cdb20a6b
> Author: David Howells <dhowells@redhat.com>
> Date:   Thu Jan 30 21:50:36 2020 +0000
>
>     rxrpc: Fix insufficient receive notification generation

This is unrelated.
Somehow the crash wasn't reproduced again on the same commit. Can it
depend on host CPU type maybe?

> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1483bb19e00000
> start commit:   b74b991f Merge tag 'block-5.6-20200320' of git://git.kerne..
> git tree:       upstream
> final crash:    https://syzkaller.appspot.com/x/report.txt?x=1683bb19e00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=1283bb19e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=6dfa02302d6db985
> dashboard link: https://syzkaller.appspot.com/bug?extid=3f29ca2efb056a761e38
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1199c0c5e00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15097373e00000
>
> Reported-by: syzbot+3f29ca2efb056a761e38@syzkaller.appspotmail.com
> Fixes: f71dbf2fb284 ("rxrpc: Fix insufficient receive notification generation")
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection