sum_overflows_off
if (off < 0 || sum_overflows_off(off, len) ||
sum_overflows_off(bfp->l_start, bfp->l_len - 1)) {
if (sum_overflows_off(entry->vde_off, (off_t)entry->vde_len)) {
if (sum_overflows_off(off, len)) {