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Index > Windows > [solved] Odd issue with 64-bit MSVCRT printf invocation

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Trinitek



Joined: 06 Nov 2011
Posts: 257
Trinitek
I've got a heisenbug on my hands. The following works on my Win7 machine and my debugger without problems, but fails on Win10.
Code:
format PE64 console
entry start

    include "win64a.inc"

section '.text' code readable executable
    
    start:
        invoke printf, msg_helloWorld
        invoke ExitProcess, 0
        
    msg_test db "Test", 0x0D, 0x0A, 0
    
section '.data' data readable

    msg_helloWorld db "Hello world!", 0x0D, 0x0A, 0
    
section '.idata' import data readable writeable

    library kernel32,'KERNEL32.DLL',\
            msvcrt, 'MSVCRT.DLL'
    
    include 'api/kernel32.inc'
    
    import  msvcrt,\
            printf, 'printf'    
Any ideas? inb4 Windows 10? More like WinBLOWS 10 am I rite???
Post 27 Mar 2017, 06:27
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17279
Location: In your JS exploiting you and your system
revolution
What do you mean by "fails on Win10"? Crashes? Prints something else? Prints nothing? Infinite loop? Can't start? Can't debug?
Post 27 Mar 2017, 06:38
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Trinitek



Joined: 06 Nov 2011
Posts: 257
Trinitek
revolution wrote:
What do you mean by "fails on Win10"? Crashes? Prints something else? Prints nothing? Infinite loop? Can't start? Can't debug?
It crashes and burns. "ConsoleTest.exe has stopped working."
Post 27 Mar 2017, 06:44
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17279
Location: In your JS exploiting you and your system
revolution
Probably because the stack is misaligned.

Try inserting this after the start label:
Code:
and rsp,-16    
Post 27 Mar 2017, 06:50
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Trinitek



Joined: 06 Nov 2011
Posts: 257
Trinitek
Stupid stack alignments. Thanks a bunch.
Post 27 Mar 2017, 06:55
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