Environment issue? Simple or not so simple?

[TimoVJL]

it works both with and without the "sub rsp, 28h"

Not aligning the stack correctly is a recipe for disaster. Many Windows APIs work just fine, but every now and then you will get mysterious crashes...

some people don't like facts and now it is very well proved.
If even depends.exe show, that program crash, who are those people ?

[zedd151]

... who are those people ?

New members that do not yet fully understand the concept of stack alignment, shadow space, etc. and other specs in the 64 bit ABI.

You should not assume that everyone knows what 'depends.exe' is or or what it does. New members often need a lot of help understanding the "how" and "why" things must be done a certain way, in words that they (as newbies) can understand.

[NoCforMe]

I've never heard of depends.exe. What and where is it?

(Doesn't have anything to do with diapers, does it?)

[Nate523]

it works both with and without the "sub rsp, 28h"

Not aligning the stack correctly is a recipe for disaster. Many Windows APIs work just fine, but every now and then you will get mysterious crashes...

some people don't like facts and now it is very well proved.
If even depends.exe show, that program crash, who are those people ?

Actually, being the newbie, I missed the last line of your depends.exe export that it crashed when loading ntdll.dll when not aligning the stack, thank you for providing that, I will have to download on my personal computer and learn how to use depends.exe because my work computer (which I was having the issue with) didn't like depends.exe. I will definitely say I think I used the word "work" incorrectly. I was trying to just say that that when I use either the stack alignment way, or not, it runs and I get the exit code I was expecting and no longer getting the exception I was running into with the Visual Studio environment. I think I understand that doesn't mean it worked, and what you showed definitely shows it didn't. Sorry for the confusion.

Still reading up on stack alignment and trying to grasp it, I will take you're word with your experience that it is a bad thing to not do.

[NoCforMe]

Stack alignment is pretty damn important to any computer system.

Probably the worst that can happen is that a subroutine return address gets lost or trashed. Think about how the CALL instruction works, which is how you access a function: the first thing it does is push the return address (the address of whatever instruction immediately follows the CALL on the stack. Then it jumps to the entry point of the subroutine and starts executing it.

So let's say that in the meantime, while the code in the subroutine is running, the stack pointer (ESP in 64 bit) gets somehow changed. When the subroutine code hits its RET instruction, it pops the stack and retrieves the return address that was pushed on the stack. But if the wrong thing gets popped, then the return will be to somewhere in never-neverland, and you'll get an exception.

Just one of the many ways you can get into trouble with code ...