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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Thu, 13 May 2021 09:08:20 +0200
Message-ID: <CACT4Y+YhQQtHBErLYRDqHyw16Bxu9FCMQymviMBR-ywiKf3VQw@mail.gmail.com>
Subject: Re: [syzbot] WARNING in __nf_unregister_net_hook (4)
To:     Pablo Neira Ayuso <pablo@netfilter.org>
Cc:     Florian Westphal <fw@strlen.de>,
        syzbot <syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com>,
        coreteam@netfilter.org, David Miller <davem@davemloft.net>,
        Jozsef Kadlecsik <kadlec@netfilter.org>,
        Jakub Kicinski <kuba@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        NetFilter <netfilter-devel@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>
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On Thu, May 13, 2021 at 2:56 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
>
> On Sat, May 08, 2021 at 04:46:57PM +0200, Florian Westphal wrote:
> > Dmitry Vyukov <dvyukov@google.com> wrote:
> > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com
> > >
> > > Is this also fixed by "netfilter: arptables: use pernet ops struct
> > > during unregister"?
> > > The warning is the same, but the stack is different...
> >
> > No, this is a different bug.
> >
> > In both cases the caller attempts to unregister a hook that the core
> > can't find, but in this case the caller is nftables, not arptables.
>
> I see no reproducer for this bug. Maybe I broke the dormant flag handling?
>
> Or maybe syzbot got here after the arptables bug has been hitted?

syzbot always stops after the first bug to give you perfect "Not
tainted" oopses.