description: arm: guest_physmap_remove_page not removing the p2m mappings The functions to remove one or more entries from a guest p2m pagetable on Arm (p2m_remove_mapping, guest_physmap_remove_page, and p2m_set_entry with mfn set to INVALID_MFN) do not actually clear the pagetable entry if the entry doesn't have the valid bit set. It is possible to have a valid pagetable entry without the valid bit set when a guest operating system uses set/way cache maintenance instructions. For instance, a guest issuing a set/way cache maintenance instruction, then calling the XENMEM_decrease_reservation hypercall to give back memory pages to Xen, might be able to retain access to those pages even after Xen started reusing them for other purposes.
problem types: unknown
affected:
{
product: xen
vendor: Xen
versions:
status: unknown, version: consult Xen advisory XSA-393
}
metrics:
other: [
content: {'description': {'description_data': [{'lang': 'eng', 'value': "A malicious guest may be able to access Xen and other domains' memory.\nThis could cause information leaks, host or domain Denial of Service\n(DoS), and privilege escalations."}]}}
type: unknown
]