QAudioInput::stop() crash in windows7.1

I use windows debug tools (global flags ) to check memory errory of my Qt application .
I found that ,when call QudioInput::stop(), my app crash ,after debugging and analysising I may found probrem ,as follows:
in qaudioinput_win32_p.cpp
void QAudioInputPrivate::close()
{
if(deviceState == QAudio::StoppedState)
return;

deviceState = QAudio::StoppedState;
waveInReset(hWaveIn);
waveInClose(hWaveIn);//

int count = 0;
while(!finished && count < 500)

mutex.lock();
for(int i=0; i<waveFreeBlockCount; i++)
waveInUnprepareHeader(hWaveIn,&waveBlocks[i],sizeof(WAVEHDR));
freeBlocks(waveBlocks);//
mutex.unlock();
}

I thought the probrem is that:
1 waveInClose is called first, and then hWaveIn become invalid.
2 waveInUnprepareHeader is called in freeBlocks() which pass it an invalid param of hWaveIn.
3 so my app crash .