{"id":"CVE-2026-72175","revision":null,"records":[{"revision":"0720fa546cfa4216b616aa47acf190bd","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-72175","aliases":[],"title":"fs/proc/task_mmu: fix make_uffd_wp_huge_pte() prot-update race","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: fix make_uffd_wp_huge_pte() prot-update race\n\nPatch series \"userfaultfd/pagemap: pre-existing fixes\".\n\nThese are pre-existing bug fixes that were carried at the front of the\nuserfaultfd RWP working-set-tracking series up to v5 [1]. Per review\nfeedback that fixes should not sit in the middle of a feature series, they\nare split out and sent on their own; the RWP series is reposted rebased on\ntop of this.\n\nAll six were flagged by the Sashiko AI review of the RWP series and carry\nindependent of RWP, apply to mm-new directly, and carry Cc: stable@.\n\n 1: fs/proc/task_mmu: a missing huge_ptep_modify_prot_start() in\n make_uffd_wp_huge_pte() can lose hardware Dirty/Accessed updates\n when PAGEMAP_SCAN write-protects a hugetlb PTE.\n\n 2: fs/proc/task_mmu: pagemap_scan_hugetlb_entry() compares the range\n against HPAGE_SIZE rather than the hstate page size, so it never\n write-protects gigantic hugetlb pages.\n\n 3: fs/proc/task_mmu: PAGEMAP_SCAN with PM_SCAN_WP_MATCHING over an\n unpopulated hugetlb range self-deadlocks -- pagemap_scan_pte_hole()\n calls uffd_wp_range() while walk_hugetlb_range() holds the hugetlb\n vma lock for read, and hugetlb_change_protection() then takes it\n for write. Install the marker inline instead.\n\n 4: mm/huge_memory: change_non_present_huge_pmd() drops pmd_swp_uffd_wp\n on a device-private PMD permission downgrade, silently losing the\n uffd-wp marker.\n\n 5: userfaultfd: must_wait() applies pte_write() to a locklessly read\n PTE without checking pte_present(), so swap/migration entries\n decode random offset bits and a thread can stay parked on a stale\n fault.\n\n 6: userfaultfd: __VMA_UFFD_FLAGS feeds VMA_UFFD_MINOR_BIT (41) to\n mk_vma_flags() unconditionally, an out-of-bounds write into the\n single-word vma_flags_t on 32-bit. Build the mask from config-gated\n per-mode masks so an unavailable bit is never materialised.\n\n\nThis patch (of 6):\n\nmake_uffd_wp_huge_pte() arms the UFFD_WP bit on a present HugeTLB PTE by\ncalling huge_ptep_modify_prot_commit() with a ptent snapshot that was\nfetched without the corresponding huge_ptep_modify_prot_start(). The\nstart helper is what atomically clears the entry so the kernel-owned\nsnapshot stays consistent until the commit; without it, the hardware may\nset Dirty or Accessed in the live PTE between the original read and the\ncommit, and huge_ptep_modify_prot_commit() (whose generic implementation\njust calls set_huge_pte_at()) then writes the stale snapshot back over the\nlive hardware bits, losing the update.\n\nThe non-hugetlb sibling make_uffd_wp_pte() does this correctly via\nptep_modify_prot_start() / ptep_modify_prot_commit(). Mirror that pattern\nfor the present-PTE branch. The migration case stays as-is -- migration\nentries are non-present, so there's no hardware update to race against.","state":0,"publishedAt":"2026-08-15T05:53:40.011+00:00","modifiedAt":"2026-10-16T18:45:00.474+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/proc/task_mmu.c\"\n ],\n \"versions\": [\n {\n \"version\": \"52526ca7fdb905a768a93f8faa418e9b988fc34b\",\n \"lessThan\": \"50a25249a6355db74c2c1b6be541b4caab9f3655\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"52526ca7fdb905a768a93f8faa418e9b988fc34b\",\n \"lessThan\": \"8e39ed92d7c5c6bfc08dc45153916f49a4e98bab\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"52526ca7fdb905a768a93f8faa418e9b988fc34b\",\n \"lessThan\": \"6b7f774b8882445d9174681747d37c42548686a4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"52526ca7fdb905a768a93f8faa418e9b988fc34b\",\n \"lessThan\": \"04718f7c9290f95385f0dd328758753dc1c36dec\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/proc/task_mmu.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.7\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.7\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.101\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.42\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.5\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":7.1,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/50a25249a6355db74c2c1b6be541b4caab9f3655","https://git.kernel.org/stable/c/8e39ed92d7c5c6bfc08dc45153916f49a4e98bab","https://git.kernel.org/stable/c/6b7f774b8882445d9174681747d37c42548686a4","https://git.kernel.org/stable/c/04718f7c9290f95385f0dd328758753dc1c36dec"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72175","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-72175","identifiers":["CVE-2026-72175"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-09T09:04:02.9162191+00:00","complete":true,"records":1769,"lastAttemptAt":"2026-11-09T09:04:02.9162191+00:00","lastSuccessAt":"2026-11-09T09:04:03.0760313+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:04:03.0760345+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-24e6fde7b744113daefb8f6135035fb8a5c69c9617c9c0d40574a0376532ffd3-0ea295a9c399a04b3ab57ccec2161d0d1cc039ee9ab5c4d8b6299048bd56b277","complete":true,"records":421333,"lastAttemptAt":"2026-11-09T09:02:14.7013141+00:00","lastSuccessAt":"2026-11-09T09:02:14.6291653+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:02:14.7013141+00:00","snapshotPublishedAt":"2026-11-09T08:31:17+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-f975b42a7c2d46f6899c3d764d777217","complete":false,"records":13654,"lastAttemptAt":"2026-11-09T09:16:12.2541949+00:00","lastSuccessAt":"2026-11-09T09:16:12.249+00:00","error":"7 identifier lookups failed; latest failures include HTTP 403. Other identifiers were checked independently.","lastVerifiedAt":"2026-11-09T09:16:12.249+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13699,"expectedIdentifiers":13706,"failedIdentifiers":7},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-09T09:04:02.9162191+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-09T09:04:02.9162191+00:00","lastSuccessAt":"2026-11-09T09:04:03.197028+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:04:03.1970284+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. 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