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 yhs@fb.com Link: https://lore.kernel.org/bpf/20211103173213.1376990-3-andrii@kernel.org 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 1cc0383471f01..c7ba5e6ed9cfe 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2753,13 +2753,12 @@ 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;