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Date:   Tue, 10 Mar 2020 16:32:28 +0900
From:   Yoshiki Komachi <>
To:     "David S. Miller" <>,
        Alexei Starovoitov <>,
        Daniel Borkmann <>,
        Martin KaFai Lau <>,
        Song Liu <>, Yonghong Song <>,
        Andrii Nakryiko <>
Cc:     Yoshiki Komachi <>,,
Subject: [PATCH v2 bpf 0/2] Fix BTF verification of enum members with a selftest

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(-)


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