CVE-2025-39845

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()

Define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure

page tables are properly synchronized when calling p*d_populate_kernel().

For 5-level paging, synchronization is performed via

pgd_populate_kernel(). In 4-level paging, pgd_populate() is a no-op, so

synchronization is instead performed at the P4D level via

p4d_populate_kernel().

This fixes intermittent boot failures on systems using 4-level paging and

a large amount of persistent memory:

BUG: unable to handle page fault for address: ffffe70000000034

#PF: supervisor write access in kernel mode

#PF: error_code(0x0002) - not-present page

PGD 0 P4D 0

Oops: 0002 [#1] SMP NOPTI

RIP: 0010:__init_single_page+0x9/0x6d

Call Trace:

<TASK>

__init_zone_device_page+0x17/0x5d

memmap_init_zone_device+0x154/0x1bb

pagemap_range+0x2e0/0x40f

memremap_pages

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References