{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31456", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.092Z", "datePublished": "2026-04-22T13:53:49.568Z", "dateUpdated": "2026-06-17T13:44:31.920Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-06-17T13:44:31.920Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/pagewalk: fix race between concurrent split and refault\n\nThe splitting of a PUD entry in walk_pud_range() can race with a\nconcurrent thread refaulting the PUD leaf entry causing it to try walking\na PMD range that has disappeared.\n\nAn example and reproduction of this is to try reading numa_maps of a\nprocess while VFIO-PCI is setting up DMA (specifically the\nvfio_pin_pages_remote call) on a large BAR for that process.\n\nThis will trigger a kernel BUG:\nvfio-pci 0000:03:00.0: enabling device (0000 -> 0002)\nBUG: unable to handle page fault for address: ffffa23980000000\nPGD 0 P4D 0\nOops: Oops: 0000 [#1] SMP NOPTI\n...\nRIP: 0010:walk_pgd_range+0x3b5/0x7a0\nCode: 8d 43 ff 48 89 44 24 28 4d 89 ce 4d 8d a7 00 00 20 00 48 8b 4c 24\n28 49 81 e4 00 00 e0 ff 49 8d 44 24 ff 48 39 c8 4c 0f 43 e3 <49> f7 06\n 9f ff ff ff 75 3b 48 8b 44 24 20 48 8b 40 28 48 85 c0 74\nRSP: 0018:ffffac23e1ecf808 EFLAGS: 00010287\nRAX: 00007f44c01fffff RBX: 00007f4500000000 RCX: 00007f44ffffffff\nRDX: 0000000000000000 RSI: 000ffffffffff000 RDI: ffffffff93378fe0\nRBP: ffffac23e1ecf918 R08: 0000000000000004 R09: ffffa23980000000\nR10: 0000000000000020 R11: 0000000000000004 R12: 00007f44c0200000\nR13: 00007f44c0000000 R14: ffffa23980000000 R15: 00007f44c0000000\nFS: 00007fe884739580(0000) GS:ffff9b7d7a9c0000(0000)\nknlGS:0000000000000000\nCS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: ffffa23980000000 CR3: 000000c0650e2005 CR4: 0000000000770ef0\nPKRU: 55555554\nCall Trace:\n \n __walk_page_range+0x195/0x1b0\n walk_page_vma+0x62/0xc0\n show_numa_map+0x12b/0x3b0\n seq_read_iter+0x297/0x440\n seq_read+0x11d/0x140\n vfs_read+0xc2/0x340\n ksys_read+0x5f/0xe0\n do_syscall_64+0x68/0x130\n ? get_page_from_freelist+0x5c2/0x17e0\n ? mas_store_prealloc+0x17e/0x360\n ? vma_set_page_prot+0x4c/0xa0\n ? __alloc_pages_noprof+0x14e/0x2d0\n ? __mod_memcg_lruvec_state+0x8d/0x140\n ? __lruvec_stat_mod_folio+0x76/0xb0\n ? __folio_mod_stat+0x26/0x80\n ? do_anonymous_page+0x705/0x900\n ? __handle_mm_fault+0xa8d/0x1000\n ? __count_memcg_events+0x53/0xf0\n ? handle_mm_fault+0xa5/0x360\n ? do_user_addr_fault+0x342/0x640\n ? arch_exit_to_user_mode_prepare.constprop.0+0x16/0xa0\n ? irqentry_exit_to_user_mode+0x24/0x100\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\nRIP: 0033:0x7fe88464f47e\nCode: c0 e9 b6 fe ff ff 50 48 8d 3d be 07 0b 00 e8 69 01 02 00 66 0f 1f\n84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00\n f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28\nRSP: 002b:00007ffe6cd9a9b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000\nRAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007fe88464f47e\nRDX: 0000000000020000 RSI: 00007fe884543000 RDI: 0000000000000003\nRBP: 00007fe884543000 R08: 00007fe884542010 R09: 0000000000000000\nR10: fffffffffffffbc5 R11: 0000000000000246 R12: 0000000000000000\nR13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000\n \n\nFix this by validating the PUD entry in walk_pmd_range() using a stable\nsnapshot (pudp_get()). If the PUD is not present or is a leaf, retry the\nwalk via ACTION_AGAIN instead of descending further. This mirrors the\nretry logic in walk_pte_range(), which lets walk_pmd_range() retry if the\nPTE is not being got by pte_offset_map_lock()." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "mm/pagewalk.c" ], "versions": [ { "version": "f9e54c3a2f5b79ecc57c7bc7d0d3521e461a2101", "lessThan": "138ada1337b47cc5efb08e517674d46f86268274", "status": "affected", "versionType": "git" }, { "version": "f9e54c3a2f5b79ecc57c7bc7d0d3521e461a2101", "lessThan": "38ec58670a0c5fc1edabdeccd857e586b7b3f318", "status": "affected", "versionType": "git" }, { "version": "f9e54c3a2f5b79ecc57c7bc7d0d3521e461a2101", "lessThan": "9bbbebd94dd5be25ec8c899d46ef01b33d5d22c0", "status": "affected", "versionType": "git" }, { "version": "f9e54c3a2f5b79ecc57c7bc7d0d3521e461a2101", "lessThan": "3b89863c3fa482912911cd65a12a3aeef662c250", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "mm/pagewalk.c" ], "versions": [ { "version": "6.12", "status": "affected" }, { "version": "0", "lessThan": "6.12", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.84", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.21", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.11", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "6.12.84" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "6.18.21" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "6.19.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/138ada1337b47cc5efb08e517674d46f86268274" }, { "url": "https://git.kernel.org/stable/c/38ec58670a0c5fc1edabdeccd857e586b7b3f318" }, { "url": "https://git.kernel.org/stable/c/9bbbebd94dd5be25ec8c899d46ef01b33d5d22c0" }, { "url": "https://git.kernel.org/stable/c/3b89863c3fa482912911cd65a12a3aeef662c250" } ], "title": "mm/pagewalk: fix race between concurrent split and refault", "x_generator": { "engine": "bippy-1.2.0" } } } }