const LayerWebKitThread* LayerWebKitThread::rootLayer() const
{
    const LayerWebKitThread* layer = this;
    LayerWebKitThread* superlayer = layer->superlayer();

    while (superlayer) {
        layer = superlayer;
        superlayer = superlayer->superlayer();
    }
    return layer;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.