ofp-actions: Avoid buffer overread in BUNDLE action decoding.

Reported-at: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=9052
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Justin Pettit <jpettit@ovn.org>
decode_NXAST_RAW_STACK_POP(const struct nx_action_stack *nasp,
                           enum ofp_version ofp_version OVS_UNUSED,
                           const struct vl_mff_map *vl_mff_map,
                           uint64_t *tlv_bitmap, struct ofpbuf *ofpacts)
{
    struct ofpact_stack *pop = ofpact_put_STACK_POP(ofpacts);
    enum ofperr error = decode_stack_action(nasp, vl_mff_map, tlv_bitmap,
                                            pop);
    return error ? error : nxm_stack_pop_check(pop, NULL);
}

decode_NXAST_RAW_STACK_POP(const struct nx_action_stack *nasp,
                           enum ofp_version ofp_version OVS_UNUSED,
                           const struct vl_mff_map *vl_mff_map,
                           uint64_t *tlv_bitmap, struct ofpbuf *ofpacts)
{
    struct ofpact_stack *pop = ofpact_put_STACK_POP(ofpacts);
    enum ofperr error = decode_stack_action(nasp, vl_mff_map, tlv_bitmap,
                                            pop);
    return error ? error : nxm_stack_pop_check(pop, NULL);
}
