From: Yonghong Song <yhs@fb.com>
To: Andrii Nakryiko <andrii@kernel.org>, <bpf@vger.kernel.org>,
<netdev@vger.kernel.org>, <ast@fb.com>, <daniel@iogearbox.net>
Cc: <kernel-team@fb.com>, Dmitrii Banshchikov <dbanschikov@fb.com>
Subject: Re: [PATCH bpf] libbpf: don't attempt to load unused subprog as an entry-point BPF program
Date: Sun, 8 Nov 2020 22:13:52 -0800 [thread overview]
Message-ID: <67fdbee5-14ba-360b-269f-d7030bd7062a@fb.com> (raw)
In-Reply-To: <20201107000251.256821-1-andrii@kernel.org>
On 11/6/20 4:02 PM, Andrii Nakryiko wrote:
> If BPF code contains unused BPF subprogram and there are no other subprogram
> calls (which can realistically happen in real-world applications given
> sufficiently smart Clang code optimizations), libbpf will erroneously assume
> that subprograms are entry-point programs and will attempt to load them with
> UNSPEC program type.
>
> Fix by not relying on subcall instructions and rather detect it based on the
> structure of BPF object's sections.
>
> Reported-by: Dmitrii Banshchikov <dbanschikov@fb.com>
> Fixes: 9a94f277c4fb ("tools: libbpf: restore the ability to load programs from .text section")
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
next prev parent reply other threads:[~2020-11-09 6:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-07 0:02 [PATCH bpf] libbpf: don't attempt to load unused subprog as an entry-point BPF program Andrii Nakryiko
2020-11-09 6:13 ` Yonghong Song [this message]
2020-11-09 21:19 ` John Fastabend
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