On Wed, Jun 19, 2019 at 12:01 PM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote:
>
> Commit 1dc92851849c ("bpf: kernel side support for BTF Var and DataSec")
> added invocations of btf_type_is_resolve_source_only before
> btf_type_nosize_or_null which checks for the NULL pointer.
> Swap the order of btf_type_nosize_or_null and
> btf_type_is_resolve_source_only to make sure the do the NULL pointer
> check first.
>
> Fixes: 1dc92851849c ("bpf: kernel side support for BTF Var and DataSec")
> Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
> Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> ---
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> kernel/bpf/btf.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index cad09858a5f2..546ebee39e2a 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -1928,8 +1928,8 @@ static int btf_array_resolve(struct btf_verifier_env *env,
> /* Check array->index_type */
> index_type_id = array->index_type;
> index_type = btf_type_by_id(btf, index_type_id);
> - if (btf_type_is_resolve_source_only(index_type) ||
> - btf_type_nosize_or_null(index_type)) {
> + if (btf_type_nosize_or_null(index_type) ||
> + btf_type_is_resolve_source_only(index_type)) {
> btf_verifier_log_type(env, v->t, "Invalid index");
> return -EINVAL;
> }
> @@ -1948,8 +1948,8 @@ static int btf_array_resolve(struct btf_verifier_env *env,
> /* Check array->type */
> elem_type_id = array->type;
> elem_type = btf_type_by_id(btf, elem_type_id);
> - if (btf_type_is_resolve_source_only(elem_type) ||
> - btf_type_nosize_or_null(elem_type)) {
> + if (btf_type_nosize_or_null(elem_type) ||
> + btf_type_is_resolve_source_only(elem_type)) {
> btf_verifier_log_type(env, v->t,
> "Invalid elem");
> return -EINVAL;
> @@ -2170,8 +2170,8 @@ static int btf_struct_resolve(struct btf_verifier_env *env,
> const struct btf_type *member_type = btf_type_by_id(env->btf,
> member_type_id);
>
> - if (btf_type_is_resolve_source_only(member_type) ||
> - btf_type_nosize_or_null(member_type)) {
> + if (btf_type_nosize_or_null(member_type) ||
> + btf_type_is_resolve_source_only(member_type)) {
> btf_verifier_log_member(env, v->t, member,
> "Invalid member");
> return -EINVAL;
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
