memory leak when using COM IDispatch::GetTypeInfo() in C#

Question

I have the following function in a COM dll (C#, .NET framework v2):

public void Leak(object jsObject) {
    Type comType;
    IDispatch disp = (IDispatch)jsObject;
    disp.GetTypeInfo(0, 0, out comType); // this line causes the leak
    Marshal.FinalReleaseComObject(disp);
    Marshal.FinalReleaseComObject(jsObject);
    disp = null;
    jsObject = null;
    GC.Collect(); GC.WaitForPendingFinalizers();
}

When calling this function repeatedly from a JScript, it leaks lots of memory:

var util = new ActiveXObject('MyLeakyCOM.MyLeakyCOM');

for(var i = 0; i < 1000; i++) {
    util.Leak({});
}

I've already tried to release the object with while(Marshal.ReleaseComObject(disp) > 0) {} but also no luck.

Answer 1

I'm a C++ guy rather than a C# guy, but it strikes me that you should also be releasing comType:

Marshal.FinalReleaseComObject(comType);

The ITypeInfo object is a proper COM object and it's AddRef will have been called by the implementation of GetTypeInfo.