Interesting... it never occurred to me that brute forcing an address was feasible enough to bother with. ;P (edit: Although, thinking more, some exploits have a more constrained range of addresses. That said, even here we have a 2-3GB area, but could probably expand the target to "any instruction executed between these points", which might be as much as a kilobyte; requiring just a few million attempts isn't that unreasonable.)

Looking at GRKERNSEC_BRUTE, however, it would not affect this exploit: it is designed to penalize the parent for forking exploitable children (so as, for example, to keep new copies of Apache from coming into existence rapidly enough for them to be remotely exploited); however, here we are assumed to have control of the parent, so we can just add a layer of indirection, never reusing direct parents.