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From:   Hsin-Wei Hung <hsinweih@uci.edu>
Date:   Fri, 24 Feb 2023 09:58:37 -0600
Message-ID: <CABcoxUYiRUBkhzsbvsux8=zjgs7KKWYUobjoKrM+JYpeyfNw8g@mail.gmail.com>
Subject: Re: A potential deadlock in sockhash map
To:     Jakub Sitnicki <jakub@cloudflare.com>
Cc:     John Fastabend <john.fastabend@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org
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Hi Jakub,

Thanks for following up. Sorry that I did not receive the previous reply.

The latest version I tested is 5.19 (3d7cb6b04c3f) and we can reproduce the
issue with the BPF PoC included. Since we modified Syzkaller, we do not
have a Syzkaller reproducer.

I will follow John's suggestion to test the latest kernel and bpf
tree. I will follow
up if the issue still reproduces.

Thanks,
Hsin-Wei


On Fri, Feb 24, 2023 at 8:51 AM Jakub Sitnicki <jakub@cloudflare.com> wrote:
>
> Hi,
>
> On Mon, Feb 20, 2023 at 07:39 AM -06, Hsin-Wei Hung wrote:
> > I think my previous report got blocked since it contained HTML
> > subparts so I am sending it again. Our bpf runtime fuzzer (a
> > customized syzkaller) triggered a lockdep warning in the bpf subsystem
> > indicating a potential deadlock. We are able to trigger this bug on
> > v5.15.25 and v5.19. The following code is a BPF PoC, and the lockdep
> > warning is attached at the end.
>
> Not sure if you've seen John's reply to the previous report:
>
> https://urldefense.com/v3/__https://lore.kernel.org/all/63dddcc92fc31_6bb15208e9@john.notmuch/__;!!CzAuKJ42GuquVTTmVmPViYEvSg!PU-LFxMnx4b-GmTXGI0hYjBiq8vkwrFrlf_b0N5uzy8do5kPFiNcuZJbby-19TtOH2rJoY9UwOvzFArd$
>
> Are you also fuzzing any newer kernel versions? Or was v5.19 the latest?
>
> Did syzkaller find a reproducer?
>
> Thanks,
> Jakub