mf: Fix GetClock() for shutdown state.

dlls/mf/session.c

@@ -1364,13 +1364,19 @@ static HRESULT WINAPI mfsession_Shutdown(IMFMediaSession *iface)
 static HRESULT WINAPI mfsession_GetClock(IMFMediaSession *iface, IMFClock **clock)
 {
     struct media_session *session = impl_from_IMFMediaSession(iface);
+    HRESULT hr;
 
     TRACE("%p, %p.\n", iface, clock);
 
-    *clock = (IMFClock *)session->clock;
-    IMFClock_AddRef(*clock);
+    EnterCriticalSection(&session->cs);
+    if (SUCCEEDED(hr = session_is_shut_down(session)))
+    {
+        *clock = (IMFClock *)session->clock;
+        IMFClock_AddRef(*clock);
+    }
+    LeaveCriticalSection(&session->cs);
 
-    return S_OK;
+    return hr;
 }
 
 static HRESULT WINAPI mfsession_GetSessionCapabilities(IMFMediaSession *iface, DWORD *caps)

dlls/mf/tests/mf.c

@@ -1100,6 +1100,7 @@ todo_wine
 
     hr = IMFClock_GetProperties(clock, &clock_props);
     ok(hr == MF_E_CLOCK_NO_TIME_SOURCE, "Unexpected hr %#x.\n", hr);
+    IMFClock_Release(clock);
 
     IMFRateControl_Release(rate_control);
     IMFRateSupport_Release(rate_support);
@@ -1117,6 +1118,9 @@ todo_wine
     hr = IMFMediaSession_Close(session);
     ok(hr == MF_E_SHUTDOWN, "Unexpected hr %#x.\n", hr);
 
+    hr = IMFMediaSession_GetClock(session, &clock);
+    ok(hr == MF_E_SHUTDOWN, "Unexpected hr %#x.\n", hr);
+
     IMFMediaSession_Release(session);
 
     /* Custom topology loader, GUID is not registered. */