Access violation exception in 64bit MFC version


I am trying to port a 32bit application to 64 bit. The calculations appear to run correctly, but I cannot configure the views properly. I am using MFC, C++ and OpenGL, Intel 10.0.027 compiler inside VS2005 on a W7 x64 machine.

When the crash happens, I get the following message: "First-chance exception at 0xffffffff8043b1b6 in 3DApp.exe: 0xC0000005: Access violation at location 0xffffffff8043b1b6" and this is the stack trace:

user32.dll!UserCallWinProcCheckWow()  + 0x11d bytes 
user32.dll!DispatchMessageWorker()  + 0x12a bytes   
3DApp.exe!AfxInternalPumpMessage()  Line 183    C++
3DApp.exe!CWinThread::PumpMessage()  Line 896   C++
3DApp.exe!CWinThread::Run()  Line 625 + 0x13 bytes  C++

NOTE PLEASE why is UserCallWinProcCheckWow called, I thought Wow suffix was only for emulating 32 bit applications on 64 bit computer

Obviously, somewhere a 64 bit pointer gets treated as a 32 bit pointer, but I cannot pin point where that happens. I loaded debug symbols from microsoft, which show the top of the call stack.

Any help greatly appreciated. Leon


The code calling DispatchMessage is:

    if (pState->m_msgCur.message != WM_KICKIDLE && !AfxPreTranslateMessage(&(pState->m_msgCur)))

The pointers of pState appear to be 64 bit at this stage.

State of pState->m_msgCu:

  • pState->m_msgCur {msg=0x00000022 wp=0x0000000000000000 lp=0x0000000000000000} tagMSG
  • hwnd 0x0000000000020416 {unused=0x00000000 } HWND__ * message 0x00000022 unsigned int wParam 0x0000000000000000 unsigned __int64 lParam 0x0000000000000000 __int64 time 0x000f3967 unsigned long
  • pt {x=0x0000030f y=0x00000356} tagPOINT
asked on Stack Overflow Feb 28, 2011 by Leon • edited Feb 28, 2011 by Leon

3 Answers


I have just fixed an issue with the same behavior. The bug was in passing parameters to SetWindowLongPtr( GWLP_WNDPROC ), pointer to WndProc was improperly casted to LONG instead of correct LONG_PTR. This way, bad pointer to WndProc was put into internal OS WND struct, so any following call to the HWND's WndProc crashed.

answered on Stack Overflow Jun 2, 2011 by martin

It looks like the the problem is happening in a call to DispatchMessage inside MFC. It would be helpful if you'd post the parameters to this call.

answered on Stack Overflow Feb 28, 2011 by Steve

OK, 0x00000022 is the WM_CHILDACTIVATE mesasage. It takes no parameters, so it can't be a problem with those. The only other possible cause that springs to mind is that the window prodedure isn't valid. For example, the DLL that contains it could have been unloaded or the window could have been subclassed with an invalid address.

answered on Stack Overflow Feb 28, 2011 by Steve

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