    void add(const RenderLayer* layer, const IntRect& bounds)
    {
        ASSERT(m_overlapStack.size() >= 2);
        m_overlapStack[m_overlapStack.size() - 2].add(bounds);
        m_layers.add(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.