Commit 401891a9 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

libbpf: Fix potential misaligned memory access in btf_ext__new() 

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: 2993e051 ("tools/bpf: add support to read .BTF.ext sections")
Reported-by: default avatarEvgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-3-andrii@kernel.org
parent 1144ab9b

tools/lib/bpf/btf.c

+5 −5
Original line number Diff line number Diff line
@@ -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;

tools/lib/bpf/btf.h

+1 −1
Original line number Diff line number Diff line
@@ -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);