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libbpf: Fix potential misaligned memory access in btf_ext__new()

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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
This commit is contained in:
Andrii Nakryiko 2021-11-23 16:23:14 -08:00 committed by Daniel Borkmann
parent 1144ab9bdf
commit 401891a9de
2 changed files with 6 additions and 6 deletions
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10
tools/lib/bpf/btf.c
View File

@ -2731,15 +2731,11 @@ void btf_ext__free(struct btf_ext *btf_ext)
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, __u32 size)
}
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;

2
tools/lib/bpf/btf.h
View File

@ -157,7 +157,7 @@ LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
__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);