Fix resolving IWeakReference from different context #1301
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… can end up treating IUnknown as the IWeakReference interface
jlaanstra
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Mar 16, 2023
dongle-the-gadget
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Jul 29, 2023
* Fix issue with weak reference when marshaled across contexts where we can end up treating IUnknown as the IWeakReference interface * Slight refactor
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Taking the findings from #1300 and putting in a slightly different fix. Reusing the test case from it.
For weak references, when they are accessed from a different context, we use the agile reference to resolve a pointer in the current context. This ptr doesn't necessarily point to the same interface / vtbl from when we initially created it. Instead, it can point to IUnknown and can cause unexpected issues when we call it with the assumption it is the IWeakReference vftbl. This fix ensures we retrieve the pointer on the right context by making sure IObjectReference is aware of the IID it was initially created for which means it can use it when resolving the agile reference.