Re: [PATCH v3] bpf: fix uapi bpf_prog_info fields alignment
From: Song Liu <hidden>
Date: 2019-06-28 20:19:16
Also in:
bpf, linux-arch
On Thu, Jun 27, 2019 at 9:11 PM Baruch Siach [off-list ref] wrote:
Merge commit 1c8c5a9d38f60 ("Merge
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next") undid the
fix from commit 36f9814a494 ("bpf: fix uapi hole for 32 bit compat
applications") by taking the gpl_compatible 1-bit field definition from
commit b85fab0e67b162 ("bpf: Add gpl_compatible flag to struct
bpf_prog_info") as is. That breaks architectures with 16-bit alignment
like m68k. Add 31-bit pad after gpl_compatible to restore alignment of
following fields.
Thanks to Dmitry V. Levin his analysis of this bug history.
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>Acked-by: Song Liu <redacted>
quoted hunk ↗ jump to hunk
--- v3: Use alignment pad as Alexei Starovoitov suggested v2: Use anonymous union with pad to make it less likely to break again in the future. --- include/uapi/linux/bpf.h | 1 + tools/include/uapi/linux/bpf.h | 1 + 2 files changed, 2 insertions(+)diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index a8b823c30b43..29a5bc3d5c66 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h@@ -3143,6 +3143,7 @@ struct bpf_prog_info { char name[BPF_OBJ_NAME_LEN]; __u32 ifindex; __u32 gpl_compatible:1; + __u32 :31; /* alignment pad */ __u64 netns_dev; __u64 netns_ino; __u32 nr_jited_ksyms;diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index a8b823c30b43..29a5bc3d5c66 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h@@ -3143,6 +3143,7 @@ struct bpf_prog_info { char name[BPF_OBJ_NAME_LEN]; __u32 ifindex; __u32 gpl_compatible:1; + __u32 :31; /* alignment pad */ __u64 netns_dev; __u64 netns_ino; __u32 nr_jited_ksyms; --2.20.1