From: Andrii Nakryiko <andrii@kernel.org>
Date: Tue, 23 Nov 2021 16:23:14 -0800
Subject: libbpf: Fix potential misaligned memory access in btf_ext__new()
Patch-mainline: v5.17-rc1
Git-commit: 401891a9debaf0a684502f2aaecf53448cee9414
References: jsc#PED-1377
Perform a memory copy before we do the sanity checks of btf_ext_hdr.
This prevents misaligned memory access if raw btf_ext data is not 4-byte
aligned ([0]).
While at it, also add missing const qualifier.
[0] Closes: https://github.com/libbpf/libbpf/issues/391
Fixes: 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-3-andrii@kernel.org
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
tools/lib/bpf/btf.c | 10 +++++-----
tools/lib/bpf/btf.h | 2 +-
2 files changed, 6 insertions(+), 6 deletions(-)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -2731,15 +2731,11 @@ void btf_ext__free(struct btf_ext *btf_e
free(btf_ext);
}
-struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
+struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
{
struct btf_ext *btf_ext;
int err;
- err = btf_ext_parse_hdr(data, size);
- if (err)
- return libbpf_err_ptr(err);
-
btf_ext = calloc(1, sizeof(struct btf_ext));
if (!btf_ext)
return libbpf_err_ptr(-ENOMEM);
@@ -2752,6 +2748,10 @@ struct btf_ext *btf_ext__new(__u8 *data,
}
memcpy(btf_ext->data, data, size);
+ err = btf_ext_parse_hdr(btf_ext->data, size);
+ if (err)
+ goto done;
+
if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
err = -EINVAL;
goto done;
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -157,7 +157,7 @@ LIBBPF_API int btf__get_map_kv_tids(cons
__u32 expected_value_size,
__u32 *key_type_id, __u32 *value_type_id);
-LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
+LIBBPF_API struct btf_ext *btf_ext__new(const __u8 *data, __u32 size);
LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext,
__u32 *size);