ghsa-3r4w-f43v-9fpg
Vulnerability from github
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 ...]
{
"affected": [],
"aliases": [
"CVE-2025-39845"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-09-19T16:15:43Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()\n\nDefine ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure\npage tables are properly synchronized when calling p*d_populate_kernel().\n\nFor 5-level paging, synchronization is performed via\npgd_populate_kernel(). In 4-level paging, pgd_populate() is a no-op, so\nsynchronization is instead performed at the P4D level via\np4d_populate_kernel().\n\nThis fixes intermittent boot failures on systems using 4-level paging and\na large amount of persistent memory:\n\n BUG: unable to handle page fault for address: ffffe70000000034\n #PF: supervisor write access in kernel mode\n #PF: error_code(0x0002) - not-present page\n PGD 0 P4D 0\n Oops: 0002 [#1] SMP NOPTI\n RIP: 0010:__init_single_page+0x9/0x6d\n Call Trace:\n \u003cTASK\u003e\n __init_zone_device_page+0x17/0x5d\n memmap_init_zone_device+0x154/0x1bb\n pagemap_range+0x2e0/0x40f\n memremap_pages+0x10b/0x2f0\n devm_memremap_pages+0x1e/0x60\n dev_dax_probe+0xce/0x2ec [device_dax]\n dax_bus_probe+0x6d/0xc9\n [... snip ...]\n \u003c/TASK\u003e\n\nIt also fixes a crash in vmemmap_set_pmd() caused by accessing vmemmap\nbefore sync_global_pgds() [1]:\n\n BUG: unable to handle page fault for address: ffffeb3ff1200000\n #PF: supervisor write access in kernel mode\n #PF: error_code(0x0002) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0002 [#1] PREEMPT SMP NOPTI\n Tainted: [W]=WARN\n RIP: 0010:vmemmap_set_pmd+0xff/0x230\n \u003cTASK\u003e\n vmemmap_populate_hugepages+0x176/0x180\n vmemmap_populate+0x34/0x80\n __populate_section_memmap+0x41/0x90\n sparse_add_section+0x121/0x3e0\n __add_pages+0xba/0x150\n add_pages+0x1d/0x70\n memremap_pages+0x3dc/0x810\n devm_memremap_pages+0x1c/0x60\n xe_devm_add+0x8b/0x100 [xe]\n xe_tile_init_noalloc+0x6a/0x70 [xe]\n xe_device_probe+0x48c/0x740 [xe]\n [... snip ...]",
"id": "GHSA-3r4w-f43v-9fpg",
"modified": "2025-09-22T21:30:17Z",
"published": "2025-09-22T21:30:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39845"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/26ff568f390a531d1bd792e49f1a401849921960"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5f761d40ee95d2624f839c90ebeef2d5c55007f5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6659d027998083fbb6d42a165b0c90dc2e8ba989"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6bf9473727569e8283c1e2445c7ac42cf4fc9fa9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/744ff519c72de31344a627eaf9b24e9595aae554"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b7f4051dd3388edd30e9a6077c05c486aa31e0d4"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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