static int vfio_pci_intx_unmask_handler(void *opaque, void *unused)
{
	struct vfio_pci_device *vdev = opaque;
	struct pci_dev *pdev = vdev->pdev;
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&vdev->irqlock, flags);

	/*
	 * Unmasking comes from ioctl or config, so again, have the
	 * physical bit follow the virtual even when not using INTx.
	 */
	if (unlikely(!is_intx(vdev))) {
		if (vdev->pci_2_3)
			pci_intx(pdev, 1);
	} else if (vdev->ctx[0].masked && !vdev->virq_disabled) {
		/*
		 * A pending interrupt here would immediately trigger,
		 * but we can avoid that overhead by just re-sending
		 * the interrupt to the user.
		 */
		if (vdev->pci_2_3) {
			if (!pci_check_and_unmask_intx(pdev))
				ret = 1;
		} else
			enable_irq(pdev->irq);

		vdev->ctx[0].masked = (ret > 0);
	}

	spin_unlock_irqrestore(&vdev->irqlock, flags);

	return ret;
}

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.