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roticv



Joined: 19 Jun 2003
Posts: 374
Location: Singapore
roticv
At some part of my code there is a call to messagebox. However it always crashes with

---------------------------
myapplication.exe - Application Error
---------------------------
The instruction at "0x77fcb032" referenced memory at "0x007e0049". The memory could not be "written".


Click on OK to terminate the program
---------------------------
OK
---------------------------

The only way I found out that removes this error is by placing a call to the MessageBox at entrypoint. Does anyone knows what went wrong?
Post 04 Oct 2003, 14:31
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roticv



Joined: 19 Jun 2003
Posts: 374
Location: Singapore
roticv
Just to add, in ollydbg, the problem does not persist. grr.
Post 04 Oct 2003, 14:39
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Yawgmoth



Joined: 20 Aug 2003
Posts: 37
Yawgmoth
Post your code.
Post 04 Oct 2003, 18:18
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roticv



Joined: 19 Jun 2003
Posts: 374
Location: Singapore
roticv
Code:
        or      ecx, -1
        mov     edi, Invalid
        push    0C3F97523h        ;decrypt string in stack
        push    0F348041h
        mov     eax, esp
        call    eax
        pop     eax
        pop     eax             ;empty stack
        invoke  MessageBox,0,Invalid,0,0  
    
Post 05 Oct 2003, 04:24
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MazeGen



Joined: 06 Oct 2003
Posts: 975
Location: Czechoslovakia
MazeGen
Quote:

The instruction at "0x77fcb032" referenced memory at "0x007e0049". The memory could not be "written".


Looks really weird. What about that:
Code:
0x77fcb032 disassembly (reverse order):
32 B0 FC 77 .. ..    XOR DH,[EAX+....77FC]   ; referenced to 007e0049?
    

Is your de/crypting routine all right?

Else it may get out of synchronization:
Code:
32 B0              ???
FC                       CLD
77 xx            JA $+xx
    

or
Code:
32                      ???
B0 FC            MOV AL,FC
77 xx              JA $+xx
    

_________________
x86asm.net
Post 06 Oct 2003, 08:22
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roticv



Joined: 19 Jun 2003
Posts: 374
Location: Singapore
roticv
I do not know what is wrong. The weird thing is that no such error exist in ollydbg, making the debugging pain in the a**. Yes, the decrypting routine is definitely correct. At the beginning, the following snipplet works well for me, but after coding another 300 lines I got that weird error. The only way I could get rid of it is to put a messagebox somewhere before it.
Post 06 Oct 2003, 14:02
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