[PATCH AUTOSEL 5.16 009/217] libbpf: Improve sanity checking during BTF fix up
From: Sasha Levin <sashal@kernel.org>
Date: 2022-01-18 02:20:13
Also in:
bpf, lkml, stable
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
From: Andrii Nakryiko <andrii@kernel.org> [ Upstream commit 88918dc12dc357a06d8d722a684617b1c87a4654 ] 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: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <redacted> Link: https://lore.kernel.org/bpf/20211103173213.1376990-3-andrii@kernel.org (local) Signed-off-by: Sasha Levin <sashal@kernel.org> --- tools/lib/bpf/libbpf.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b5bf1c074832e..18651e11b9ba3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -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;
--
2.34.1