{"id":"AZL-74835","summary":"CVE-2025-39845 affecting package kernel for versions less than 5.15.200.1-1","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 ...]","modified":"2026-04-01T05:22:46.661Z","published":"2025-09-19T16:15:43Z","upstream":["CVE-2025-39845"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39845"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:2","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.200.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-74835.json"}}],"schema_version":"1.7.5"}