netdev - Re: [PATCH bpf] libbpf: Fix BTF-to-C conversion of noreturn function pointers

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

Date:   Mon, 8 Jun 2020 16:50:37 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Jean-Philippe Brucker <jean-philippe@...aro.org>
Cc:     bpf <bpf@...r.kernel.org>, Andrii Nakryiko <andriin@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin Lau <kafai@...com>, Song Liu <songliubraving@...com>,
        Yonghong Song <yhs@...com>,
        john fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Networking <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf] libbpf: Fix BTF-to-C conversion of noreturn function pointers

On Mon, Jun 8, 2020 at 8:23 AM Jean-Philippe Brucker
<jean-philippe@...aro.org> wrote:
>
> When trying to convert the BTF for a function pointer marked "noreturn"
> to C code, bpftool currently generates a syntax error. This happens with
> the exit() pointer in drivers/firmware/efi/libstub/efistub.h, in an
> arm64 vmlinux. When dealing with this declaration:
>
>         efi_status_t __noreturn (__efiapi *exit)(...);
>
> bpftool produces the following output:
>
>         efi_status_tvolatile  (*exit)(...);


I'm curious where this volatile is coming from, I don't see it in
__efiapi. But even if it's there, shouldn't it be inside parens
instead:

efi_status_t (volatile *exit)(...);

?

>
> Fix the error by inserting the space before the function modifier.
>
> Fixes: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion")
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
> ---

Can you please add tests for this case into selftests (probably
progs/btf_dump_test_case_syntax.c?) So it's clear what's the input and
what's the expected output.

>  tools/lib/bpf/btf_dump.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>

[...]