CVE-2025-39845
- Published: 2025-09-19T16:15:43.280
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:
__init_zone_device_page+0x17/0x5d
memmap_init_zone_device+0x154/0x1bb
pagemap_range+0x2e0/0x40f
memremap_pages+0x10b/0x2f0
devm_memremap_pages+0x1e/0x60
dev_dax_probe+0xce/0x2ec [device_dax]
dax_bus_probe+0x6d/0xc9
[… snip …]
It also fixes a crash in vmemmap_set_pmd() caused by accessing vmemmap
before sync_global_pgds() [1]:
BUG: unable to handle page fault for address: ffffeb3ff1200000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) – not-present page
PGD 0 P4D 0
Oops: Oops: 0002 [#1] PREEMPT SMP NOPTI
Tainted: [W]=WARN
RIP: 0010:vmemmap_set_pmd+0xff/0x230
vmemmap_populate_hugepages+0x176/0x180
vmemmap_populate+0x34/0x80
__populate_section_memmap+0x41/0x90
sparse_add_section+0x121/0x3e0
__add_pages+0xba/0x150
add_pages+0x1d/0x70
memremap_pages+0x3dc/0x810
devm_memremap_pages+0x1c/0x60
xe_devm_add+0x8b/0x100 [xe]
xe_tile_init_noalloc+0x6a/0x70 [xe]
xe_device_probe+0x48c/0x740 [xe]
[… snip …]
Related CVE by CWE
No related CWE found.
Top CVE for Vendor
No vendor taxonomy on this entry.
Recently Exploited Similar Vulnerabilities
No recent KEV-listed items for this vendor/product.
How to fix CVE-2025-39845
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(). […]
Exploit Difficulty: HARD
⏱️ Time to exploit: > 4 hours
🛠️ Required skills: Advanced security expertise
💰 Public exploits: Rare or not public
How to Fix:
- Check if you're running the affected product
- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access
- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)
- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations
Exploit Difficulty Assessment
Vulnerability Timeline
CVE details first published to NVD database
Added to this CVE tracking system
Detection Rules & IOCs
No specific detection rules generated for this vulnerability type.
No vendor/product data available.