[PATCH] Update tcache double-free check

[Eyal Itkin]

Hi,

Nice to see that this topic is still alive. As I said earlier,
although my initial patch was per-thread, my later analysis convinced
me that a per process solution will be a better idea.

As for the benchmarking, the cost per-thread was negligible, so I
don't see any potential risk with using the same solution (getrandom
and all) just one time per process.

Sadly, I suggest you will modify my original patch / recreate a
similar solution, as I can no longer commit new code to FSF. In the
time passed the approval of my original employer has expired (approval
was for a single year) and I also switched work place and will have to
undergo the entire legal process yet again.

Given the maturity of the current draft, I suggest you will complete
this feature based on my contribution (contribution that was made when
it was still allowed). Without an additional similar feature in the
near future, I don't see the benefit in troubling a VP for signing
again the legal docs.

Happy to see that this feature was not abandoned.

Good luck to your all, and thanks for your enthusiasm for improving
the security of such an important library.
Eyal Itkin.