I have a legacy application I’m working with which has hundreds of thousands of lines of C++ code. I am updating it to the latest version of Visual Studio, Windows SDK, etc.
The application runs fine but in a debug build on exit I get an exception:
Exception thrown at 0x560C9A11 (ucrtbased.dll) in app.exe: 0xC0000005: Access violation reading location 0xFFFFFFFC.
The call stack is:
The disassembly around this line of code is:
560C99EE mov dword ptr [ebp-2Ch],eax
560C99F1 mov ecx,dword ptr [ebp-18h]
560C99F4 mov dword ptr [ebp-20h],ecx
560C99F7 mov edx,dword ptr [ebp-14h]
560C99FA mov dword ptr [ebp-24h],edx
560C99FD mov eax,dword ptr [ebp-14h]
560C9A00 sub eax,4
560C9A03 mov dword ptr [ebp-14h],eax
560C9A06 mov ecx,dword ptr [ebp-14h]
560C9A09 cmp ecx,dword ptr [ebp-18h]
560C9A0C jb 560C9A1A
560C9A0E mov edx,dword ptr [ebp-14h]
560C9A11 mov eax,dword ptr [edx]
560C9A13 cmp eax,dword ptr [ebp-2Ch]
560C9A16 jne 560C9A1A
560C9A18 jmp 560C99FD
560C9A1A mov ecx,dword ptr [ebp-14h]
560C9A1D cmp ecx,dword ptr [ebp-18h]
560C9A20 jae 560C9A27
560C9A22 jmp 560C9AAA
560C9A27 mov edx,dword ptr [ebp-14h]
560C9A2A mov eax,dword ptr [edx]
560C9A2C push eax
560C9A2D call 560AFA70
I inherited this code base. We don’t have a lot of history in our repo. The initial commit also throws this same exception. So I can’t just go back and binary search through commits to see where it crept in. I’m guessing the exception didn’t happen in a previous version of Windows. This code base goes back to the early 2000s.
How do I go about debugging this?