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Chetan Nayak (Brute Ratel C4 Author)
@NinjaParanoid
"When you enter a function (VC++ with the stack checking enabled), it will call the _chkstk located in CHKSTK.ASM. This function does a stack page probing and causes the necessary pages of memory to be allocated using the guard page scheme, if possible."
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namazso
@namazso
Nowhere in these three quotes does it say it catches anything. "increases the stack", "causes the necessary pages of memory to be allocated". That is because it does not catch anything. It causes exceptions that are caught and memory allocated in place of the guard pages.
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namazso
@namazso
So while your supposedly source materials are correct, you interpreted it wrong, and your statement ("This exception is usually caught by the _chkstk routine") is simply just wrong. Nothing in those links and quotes says anything equivalent to that.
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namazso
@namazso
In case you're wondering where the magic *actually* happens, check nt!MiCheckForUserStackOverflow
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namazso
@namazso
That is not what your article states. It states that _chkstk catches exceptions. Can you provide a source to that?
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namazso
@namazso
Thinking that _chkstk catches anything, or that it directly allocates pages is a complete misunderstanding of how stack growing works. Stack pages are allocated by the kernel, whenever the guard pages are hit. Probing is necessary so that a single logical allocation can't skip 1/
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namazso
@namazso
over enough memory without touching anything that would result in an address past the guard pages. For small stack functions, it is not needed exactly because when they're called, the call instruction will touch the stack page when pushing the return address. 2/
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