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by BradSwain 466 days ago
> Any recursive function can be transformed into a tail recursive form, exchanging stack allocation for heap allocation. And any tail recursive program can be transformed into a loop (a trampoline)

A computer can chug through millions of loop iterations. I don't think tail recursion will ever result in heap exhaustion. But a stack overflow can be caused with tens of thousands of nested calls, which is tiny in comparison.

Recursion based stack overflow issues are easier to exploit because modern computer's stack space is much smaller relative to other resources.
1 comments
lmm 465 days ago
> Recursion based stack overflow issues are easier to exploit because modern computer's stack space is much smaller relative to other resources.

Sounds like a design issue in particular language implementations rather than a problem with the programming technique.

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Enginerrrd 465 days ago
>Sounds like a design issue in particular language implementations rather than a problem with the programming technique.

You say this like these are fundamentally separable things? I find this comment deeply confusing. Every single real software stack ever has a layer where the sausage gets made so to speak.

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fc417fc802 465 days ago
Stack overflow should not be a vulnerability for any modern tool chain. As to resource limits, LLVM has supported segmented stacks for something like a decade or maybe longer. Recursion is absolutely not the problem here. Outdated programming practices are.
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BradSwain 465 days ago
> Outdated programming practices are.

What is the outdated programming practice at fault here?

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fc417fc802 465 days ago
In the general case? The failure to compile with -fsplit-stack when that's necessary for whatever your requirements are. The failure to enable the stack protector when ... pretty much always.

For this particular CVE? I'm not clear. Possibly none. The writeup didn't provide sufficient detail and I haven't bothered to wade through the code. There may well be a reason recursion won't work here but it certainly isn't general.

I'd be curious to know in this case why resource limits couldn't be enforced for the recursive implementation but could be for the iterative one.

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