STATUS_STACK_BUFFER_OVERRUN with LoadLibrary

Question

When I load iphlpapi.dll with LoadLibrary my stack buffer overrun! How can I solve this problem?!

typedef DWORD (*GetExtendedTcpTable)(PVOID, PDWORD, BOOL, ULONG, TCP_TABLE_CLASS, ULONG);   
GetExtendedTcpTable _GetExtendedTcpTable;

// load function at runtime 
HINSTANCE hstLibrary = LoadLibrary("C:\\Windows\\System32\\Iphlpapi.dll");

if(!hstLibrary)
{
    ::MessageBox(NULL,"Can't load Iphlpapi.dll!\n","Error",
            MB_OK + MB_ICONEXCLAMATION + MB_TASKMODAL);

    FreeLibrary(hstLibrary); // free memory

    exit(0);
}

// load function address from dll
_GetExtendedTcpTable = (GetExtendedTcpTable)GetProcAddress(hstLibrary, "GetExtendedTcpTable");

The loading of the lib function and executing is working fine but at some point my program throws the STATUS_STACK_BUFFER_OVERRUN exception! (some point: when I comment the string operation the error occur few lines later)

When I don't use LoadLibrary and GetProcAddress(static binding) -> no buffer overrun!

Thanks and greets,

leon22

Answer 1

You need to specify calling convention:

typedef DWORD (WINAPI * GetExtendedTcpTable)(PVOID, PDWORD, BOOL, ULONG, TCP_TABLE_CLASS, ULONG);   

The default calling convention in VS is __cdecl, Windows API requires __stdcall. These differ in how the stack for arguments is handled, most notably __cdecl requires the caller to clean up whereas __stdcall requires the called function to clean up.

WINAPI is defined as __stdcall

See e.g. Calling Conventions Demystified