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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Sat, 28 Oct 2023 17:34:56 -0700
Message-ID: <CAADnVQK2nsdzviA1q_tBuh+7g6Xo6wZY2VxGR1H4ag40nNrSgg@mail.gmail.com>
Subject: Re: bpf: incorrect passing infinate loop causing rcu detected stall
 during bpf_prog_run()
To:     Hao Sun <sunhao.th@gmail.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        John Fastabend <john.fastabend@gmail.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>,
        Yonghong Song <yonghong.song@linux.dev>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>,
        bpf <bpf@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Oct 27, 2023 at 2:09=E2=80=AFAM Hao Sun <sunhao.th@gmail.com> wrote=
:
>
> Hi,
>
> The following C repro contains a bpf program that can cause rcu
> stall/soft lockup during running in bpf_prog_run(). Seems the verifier
> incorrectly passed the program with an infinite loop.
>
> C repro: https://pastebin.com/raw/ymzAxjeU

Thanks for the report.
Did you debug what exactly caused this bug?
Are you planning to work on the fix?

> Verifier's log: https://pastebin.com/raw/thZDTFJc

log is trimmed.