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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Mon, 24 Jan 2022 14:09:13 -0800
Message-ID: <CAEf4BzaOHPD72jTsdJjUa6md2AyRp2LnArNKyrKCva6pWCdzaA@mail.gmail.com>
Subject: Re: [PATCH 5.15 000/846] 5.15.17-rc1 review
To:     =?UTF-8?Q?Holger_Hoffst=C3=A4tte?= <holger@applied-asynchrony.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        open list <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>, linux@roeck-us.net,
        Shuah Khan <shuah@kernel.org>, patches@kernelci.org,
        lkft-triage@lists.linaro.org, pavel@denx.de, jonathanh@nvidia.com,
        f.fainelli@gmail.com, Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
        linux- stable <stable@vger.kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>, Yonghong Song <yhs@fb.com>
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On Mon, Jan 24, 2022 at 12:36 PM Holger Hoffst=C3=A4tte
<holger@applied-asynchrony.com> wrote:
>
> On 2022-01-24 19:31, Greg Kroah-Hartman wrote:
> > This is the start of the stable review cycle for the 5.15.17 release.
>
> Oh noes :(
>
>    DESCEND bpf/resolve_btfids
>    MKDIR     /tmp/linux-5.15.17/tools/bpf/resolve_btfids//libbpf
>    GEN     /tmp/linux-5.15.17/tools/bpf/resolve_btfids/libbpf/bpf_helper_=
defs.h
>    MKDIR   /tmp/linux-5.15.17/tools/bpf/resolve_btfids/libbpf/staticobjs/
>    CC      /tmp/linux-5.15.17/tools/bpf/resolve_btfids/libbpf/staticobjs/=
libbpf.o
> libbpf.c: In function 'bpf_object__elf_collect':
> libbpf.c:3038:31: error: invalid type argument of '->' (have 'GElf_Shdr' =
{aka 'Elf64_Shdr'})
>   3038 |                         if (sh->sh_type !=3D SHT_PROGBITS)
>        |                               ^~
> libbpf.c:3042:31: error: invalid type argument of '->' (have 'GElf_Shdr' =
{aka 'Elf64_Shdr'})
>   3042 |                         if (sh->sh_type !=3D SHT_PROGBITS)
>        |                               ^~
> make[4]: *** [/tmp/linux-5.15.17/tools/build/Makefile.build:97: /tmp/linu=
x-5.15.17/tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf.o] Error 1
> make[3]: *** [Makefile:158: /tmp/linux-5.15.17/tools/bpf/resolve_btfids/l=
ibbpf/staticobjs/libbpf-in.o] Error 2
> make[2]: *** [Makefile:44: /tmp/linux-5.15.17/tools/bpf/resolve_btfids//l=
ibbpf/libbpf.a] Error 2
> make[1]: *** [Makefile:72: bpf/resolve_btfids] Error 2
> make: *** [Makefile:1371: tools/bpf/resolve_btfids] Error 2
>
> Reverting "libbpf-validate-that-.btf-and-.btf.ext-sections-cont.patcht" a=
ka
> this one:
>
> > Andrii Nakryiko <andrii@kernel.org>
> >      libbpf: Validate that .BTF and .BTF.ext sections contain data
>
> makes it build & run fine. I looked for followups but couldn't find anyth=
ing that
> stood out, maybe the BPF folks (cc'ed) know what's missing/wrong.
>

That small fix depends on much bigger refactoring in ad23b7238474
("libbpf: Use Elf64-specific types explicitly for dealing with ELF").
I think this small fix can be dropped.

That's sort of a general rule with libbpf-related fixes, they are
usually not that critical to backport to stable, because most users
use/build libbpf from its Github mirror, which is always taken from
latest bpf-next. Libbpf is also not supposed to be used with untrusted
inputs (i.e., BPF object files) as BPF programs are loaded into the
kernel under root.


> cheers
> Holger