static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size)
{
    AcpiPciHpState *s = opaque;
     uint32_t val = 0;
     int bsel = s->hotplug_select;
 
    if (bsel < 0 || bsel >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
         return 0;
     }
    switch (addr) {
    case PCI_UP_BASE:
        val = s->acpi_pcihp_pci_status[bsel].up;
        if (!s->legacy_piix) {
            s->acpi_pcihp_pci_status[bsel].up = 0;
        }
        ACPI_PCIHP_DPRINTF("pci_up_read %" PRIu32 "\n", val);
        break;
    case PCI_DOWN_BASE:
        val = s->acpi_pcihp_pci_status[bsel].down;
        ACPI_PCIHP_DPRINTF("pci_down_read %" PRIu32 "\n", val);
        break;
    case PCI_EJ_BASE:
        /* No feature defined yet */
        ACPI_PCIHP_DPRINTF("pci_features_read %" PRIu32 "\n", val);
        break;
    case PCI_RMV_BASE:
        val = s->acpi_pcihp_pci_status[bsel].hotplug_enable;
        ACPI_PCIHP_DPRINTF("pci_rmv_read %" PRIu32 "\n", val);
        break;
    case PCI_SEL_BASE:
        val = s->hotplug_select;
        ACPI_PCIHP_DPRINTF("pci_sel_read %" PRIu32 "\n", val);
    default:
        break;
    }

    return val;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.