free的问题

         VideoRenderCallback** renderCallback;
         d->renderCount=1; 
         d->renderCallback = (VideoRenderCallback**)malloc(sizeof(VideoRenderCallback*)*d->renderCount);
         for (int i=0;i<d->renderCount;i++)
    {
        d->renderCallback[i] = (VideoRenderCallback*)malloc(sizeof(VideoRenderCallback));
    }


         for (int i=0;i<d->renderCount && d->renderCallback;i++)
    {
        free(d->renderCallback[i]);//[color=#FF0000]调用时会报错[/color]
        d->renderCallback[i]=NULL;
    }
         if (d->renderCallback)
    {
        free(d->renderCallback);//这个不会报错
        d->renderCallback=NULL;
    }