Commit 88918dc1 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

libbpf: Improve sanity checking during BTF fix up 



If BTF is corrupted DATASEC's variable type ID might be incorrect.
Prevent this easy to detect situation with extra NULL check.
Reported by oss-fuzz project.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-3-andrii@kernel.org
parent 83390787

tools/lib/bpf/libbpf.c

+2 −3
Original line number Diff line number Diff line
@@ -2752,13 +2752,12 @@ static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf, 


	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {

		t_var = btf__type_by_id(btf, vsi->type);

		var = btf_var(t_var);



		if (!btf_is_var(t_var)) {

		if (!t_var || !btf_is_var(t_var)) {

			pr_debug("Non-VAR type seen in section %s\n", name);

			return -EINVAL;

		}



		var = btf_var(t_var);

		if (var->linkage == BTF_VAR_STATIC)

			continue;