Crash connecting to graph containing filter supporting IVideoWindow interface

[mikecopperwhite]

Steps

• Open a 32-bit instance of GraphStudioNext (instance A)
• In instance A render a video file. The graph should contain a video renderer filter supporting IVideoWindow
• Open a 64-bit instance of GraphStudioNext (instance B)
• In instance B connect to remote graph in instance A

Expected : Connects to remote graph in instance A
Actual : Sometimes succeeds connecting, sometimes crashes. Stopping on a breakpoint before the crash almost always avoids the crash.

The crashing call stack is inside a call to put_Caption with crash occur in marshalling code for BSTR (see code extract below).

Probably caused by passing a raw pointer to the string data in the local variable vw_name to put_Caption rather than a proper BSTR parameter. Works in local graphs by chance but call timing is different calling a remote graph.

  CComPtr<IVideoWindow>		vw;

	hr = f->QueryInterface(IID_IVideoWindow, (void**)&vw);
	if (SUCCEEDED(hr)) {
		CString		vw_name;
		vw_name = _T("ActiveMovie Window: ") + display_name;
		vw->put_Caption(vw_name.GetBuffer());
		vw = NULL;
	}