Commit 5c3320d7 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

libbpf: Fix memory leak and optimize BTF sanitization 



Coverity's static analysis helpfully reported a memory leak introduced by
0f0e55d8 ("libbpf: Improve BTF sanitization handling"). While fixing it,
I realized that btf__new() already creates a memory copy, so there is no need
to do this. So this patch also fixes misleading btf__new() signature to make
data into a `const void *` input parameter. And it avoids unnecessary memory
allocation and copy in BTF sanitization code altogether.

Fixes: 0f0e55d8 ("libbpf: Improve BTF sanitization handling")
Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200710011023.1655008-1-andriin@fb.com
parent 2977282b

tools/lib/bpf/btf.c

+1 −1
Original line number Diff line number Diff line
@@ -397,7 +397,7 @@ void btf__free(struct btf *btf) 
	free(btf);

}



struct btf *btf__new(__u8 *data, __u32 size)

struct btf *btf__new(const void *data, __u32 size)

{

	struct btf *btf;

	int err;

tools/lib/bpf/btf.h

+1 −1
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ struct btf_ext_header { 
};



LIBBPF_API void btf__free(struct btf *btf);

LIBBPF_API struct btf *btf__new(__u8 *data, __u32 size);

LIBBPF_API struct btf *btf__new(const void *data, __u32 size);

LIBBPF_API struct btf *btf__parse_elf(const char *path,

				      struct btf_ext **btf_ext);

LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);

tools/lib/bpf/libbpf.c

+3 −8
Original line number Diff line number Diff line
@@ -2533,17 +2533,12 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj) 


	sanitize = btf_needs_sanitization(obj);

	if (sanitize) {

		const void *orig_data;

		void *san_data;

		const void *raw_data;

		__u32 sz;



		/* clone BTF to sanitize a copy and leave the original intact */

		orig_data = btf__get_raw_data(obj->btf, &sz);

		san_data = malloc(sz);

		if (!san_data)

			return -ENOMEM;

		memcpy(san_data, orig_data, sz);

		kern_btf = btf__new(san_data, sz);

		raw_data = btf__get_raw_data(obj->btf, &sz);

		kern_btf = btf__new(raw_data, sz);

		if (IS_ERR(kern_btf))

			return PTR_ERR(kern_btf);

CRA Git | Maintained and supported by SUSTech CRA and CCSE