From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Yoshiki Komachi <komachi.yoshiki@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH v2 bpf 0/2] Fix BTF verification of enum members with a selftest
Date: Tue, 10 Mar 2020 08:39:58 -0700 [thread overview]
Message-ID: <CAEf4BzYnuaeZ7s-yo7kAtHczcO5Ryc8ZGKYxWYWoFU-+WE0BRw@mail.gmail.com> (raw)
In-Reply-To: <1583825550-18606-1-git-send-email-komachi.yoshiki@gmail.com>
On Tue, Mar 10, 2020 at 12:32 AM Yoshiki Komachi
<komachi.yoshiki@gmail.com> wrote:
>
> btf_enum_check_member() checked if the size of "enum" as a struct
> member exceeded struct_size or not. Then, the function compared it
> with the size of "int". Although the size of "enum" is 4-byte by
> default (i.e., equivalent to "int"), the packing feature enables
> us to reduce it, as illustrated by the following example:
>
> struct A {
> char m;
> enum { E0, E1 } __attribute__((packed)) n;
> };
>
> With such a setup above, the bpf loader gave an error attempting
> to load it:
>
> ------------------------------------------------------------------
> ...
>
> [3] ENUM (anon) size=1 vlen=2
> E0 val=0
> E1 val=1
> [4] STRUCT A size=2 vlen=2
> m type_id=2 bits_offset=0
> n type_id=3 bits_offset=8
>
> [4] STRUCT A size=2 vlen=2
> n type_id=3 bits_offset=8 Member exceeds struct_size
>
> libbpf: Error loading .BTF into kernel: -22.
>
> ------------------------------------------------------------------
>
> The related issue was previously fixed by the commit 9eea98497951 ("bpf:
> fix BTF verification of enums"). On the other hand, this series fixes
> this issue as well, and adds a selftest program for it.
>
> Changes in v2:
> - change an example in commit message based on Andrii's review
> - add a selftest program for packed "enum" type members in struct/union
>
> Yoshiki Komachi (2):
> bpf/btf: Fix BTF verification of enum members in struct/union
> selftests/bpf: Add test for the packed enum member in struct/union
>
> kernel/bpf/btf.c | 2 +-
> tools/testing/selftests/bpf/test_btf.c | 42 ++++++++++++++++++++++++++++++++++
> 2 files changed, 43 insertions(+), 1 deletion(-)
>
> --
> 1.8.3.1
>
You should have updated patch prefix for patch #1 and #2 to [PATCH v2
bpf] as well, please do it next time,
For the series:
Acked-by: Andrii Nakryiko <andriin@fb.com>
next prev parent reply other threads:[~2020-03-10 15:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 7:32 [PATCH v2 bpf 0/2] Fix BTF verification of enum members with a selftest Yoshiki Komachi
2020-03-10 7:32 ` [PATCH bpf 1/2] bpf/btf: Fix BTF verification of enum members in struct/union Yoshiki Komachi
2020-03-10 7:32 ` [PATCH bpf 2/2] selftests/bpf: Add test for the packed enum member " Yoshiki Komachi
2020-03-10 15:39 ` Andrii Nakryiko [this message]
2020-03-10 16:46 ` [PATCH v2 bpf 0/2] Fix BTF verification of enum members with a selftest Martin KaFai Lau
2020-03-10 17:26 ` Alexei Starovoitov
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