netdev - RE: [PATCH bpf] libbpf: don't attempt to load unused subprog as an entry-point BPF program

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <5fa9b2442542d_8c0e2085b@john-XPS-13-9370.notmuch>
Date:   Mon, 09 Nov 2020 13:19:00 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, ast@...com, daniel@...earbox.net
Cc:     andrii@...nel.org, kernel-team@...com,
        Dmitrii Banshchikov <dbanschikov@...com>
Subject: RE: [PATCH bpf] libbpf: don't attempt to load unused subprog as an
 entry-point BPF program

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@...com>
> Fixes: 9a94f277c4fb ("tools: libbpf: restore the ability to load programs from .text section")
> Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
> ---

Acked-by: John Fastabend <john.fastabend@...il.com>