{"api_version":"1","generated_at":"2026-08-22T11:43:08+00:00","cve":"CVE-2026-72174","urls":{"html":"https://cve.report/CVE-2026-72174","api":"https://cve.report/api/cve/CVE-2026-72174.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72174","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72174"},"summary":{"title":"fs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole()\n\nA PAGEMAP_SCAN ioctl requesting PM_SCAN_WP_MATCHING on a hugetlb VMA hangs\nthe calling thread, unkillably, as soon as the scan reaches an unpopulated\npart of the range:\n\n  do_pagemap_scan()\n    walk_page_range()\n      walk_hugetlb_range()\n        hugetlb_vma_lock_read()           # take the vma lock for read ...\n        pagemap_scan_pte_hole()           # ... ->pte_hole() for a hole\n          uffd_wp_range()\n            change_protection()\n              hugetlb_change_protection()\n                hugetlb_vma_lock_write()  # ... and block taking it for write\n\nwalk_hugetlb_range() holds the hugetlb vma lock for read across the whole\nwalk.  A present entry goes to ->hugetlb_entry(); an unpopulated one goes\nto ->pte_hole(), i.e.  pagemap_scan_pte_hole().  To write-protect the hole\nthat handler calls uffd_wp_range(), which on a hugetlb VMA reaches\nhugetlb_change_protection() and takes the same vma lock for write.  The\nthread then blocks in down_write() waiting for the read lock it is itself\nholding.\n\nThe populated path avoids this: pagemap_scan_hugetlb_entry()\nwrite-protects the entry inline under the page-table lock and never enters\nhugetlb_change_protection().\n\nDo the same for holes.  Fault in the page table and install the uffd-wp\nmarker directly with make_uffd_wp_huge_pte() under the page-table lock,\nrather than routing through uffd_wp_range().  That is the same sequence\nhugetlb_change_protection() runs for an unpopulated entry, minus the vma\nwrite lock -- which is safe to skip because PMD sharing is disabled on\nuffd-wp VMAs (hugetlb_unshare_all_pmds() runs at registration), leaving\nnothing for that lock to serialise against.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:21:35","updated_at":"2026-08-17 06:18:17"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/e92d92bbafb264dc0518d52b846a3c07ed8d523f","name":"https://git.kernel.org/stable/c/e92d92bbafb264dc0518d52b846a3c07ed8d523f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/43b987ed35be9be21a303d1036d4241fec9943df","name":"https://git.kernel.org/stable/c/43b987ed35be9be21a303d1036d4241fec9943df","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/18b8a9700610299819d21fd0ea85d24726d17f65","name":"https://git.kernel.org/stable/c/18b8a9700610299819d21fd0ea85d24726d17f65","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a6ac03652d9edc30c2912037ac83beb42cc67f8e","name":"https://git.kernel.org/stable/c/a6ac03652d9edc30c2912037ac83beb42cc67f8e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-72174","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72174","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 52526ca7fdb905a768a93f8faa418e9b988fc34b a6ac03652d9edc30c2912037ac83beb42cc67f8e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 52526ca7fdb905a768a93f8faa418e9b988fc34b 43b987ed35be9be21a303d1036d4241fec9943df git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 52526ca7fdb905a768a93f8faa418e9b988fc34b 18b8a9700610299819d21fd0ea85d24726d17f65 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 52526ca7fdb905a768a93f8faa418e9b988fc34b e92d92bbafb264dc0518d52b846a3c07ed8d523f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.7","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.7 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.40 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72174","cve":"CVE-2026-72174","epss":"0.002000000","percentile":"0.101550000","score_date":"2026-08-17","updated_at":"2026-08-18 00:11:47"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/proc/task_mmu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a6ac03652d9edc30c2912037ac83beb42cc67f8e","status":"affected","version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","versionType":"git"},{"lessThan":"43b987ed35be9be21a303d1036d4241fec9943df","status":"affected","version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","versionType":"git"},{"lessThan":"18b8a9700610299819d21fd0ea85d24726d17f65","status":"affected","version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","versionType":"git"},{"lessThan":"e92d92bbafb264dc0518d52b846a3c07ed8d523f","status":"affected","version":"52526ca7fdb905a768a93f8faa418e9b988fc34b","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/proc/task_mmu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.7"},{"lessThan":"6.7","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.97","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.40","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.97","versionStartIncluding":"6.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.40","versionStartIncluding":"6.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"6.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"6.7","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole()\n\nA PAGEMAP_SCAN ioctl requesting PM_SCAN_WP_MATCHING on a hugetlb VMA hangs\nthe calling thread, unkillably, as soon as the scan reaches an unpopulated\npart of the range:\n\n  do_pagemap_scan()\n    walk_page_range()\n      walk_hugetlb_range()\n        hugetlb_vma_lock_read()           # take the vma lock for read ...\n        pagemap_scan_pte_hole()           # ... ->pte_hole() for a hole\n          uffd_wp_range()\n            change_protection()\n              hugetlb_change_protection()\n                hugetlb_vma_lock_write()  # ... and block taking it for write\n\nwalk_hugetlb_range() holds the hugetlb vma lock for read across the whole\nwalk.  A present entry goes to ->hugetlb_entry(); an unpopulated one goes\nto ->pte_hole(), i.e.  pagemap_scan_pte_hole().  To write-protect the hole\nthat handler calls uffd_wp_range(), which on a hugetlb VMA reaches\nhugetlb_change_protection() and takes the same vma lock for write.  The\nthread then blocks in down_write() waiting for the read lock it is itself\nholding.\n\nThe populated path avoids this: pagemap_scan_hugetlb_entry()\nwrite-protects the entry inline under the page-table lock and never enters\nhugetlb_change_protection().\n\nDo the same for holes.  Fault in the page table and install the uffd-wp\nmarker directly with make_uffd_wp_huge_pte() under the page-table lock,\nrather than routing through uffd_wp_range().  That is the same sequence\nhugetlb_change_protection() runs for an unpopulated entry, minus the vma\nwrite lock -- which is safe to skip because PMD sharing is disabled on\nuffd-wp VMAs (hugetlb_unshare_all_pmds() runs at registration), leaving\nnothing for that lock to serialise against."}],"providerMetadata":{"dateUpdated":"2026-08-17T05:09:36.416Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a6ac03652d9edc30c2912037ac83beb42cc67f8e"},{"url":"https://git.kernel.org/stable/c/43b987ed35be9be21a303d1036d4241fec9943df"},{"url":"https://git.kernel.org/stable/c/18b8a9700610299819d21fd0ea85d24726d17f65"},{"url":"https://git.kernel.org/stable/c/e92d92bbafb264dc0518d52b846a3c07ed8d523f"}],"title":"fs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72174","datePublished":"2026-08-15T05:53:39.276Z","dateReserved":"2026-08-09T03:40:39.910Z","dateUpdated":"2026-08-17T05:09:36.416Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:21:35","lastModifiedDate":"2026-08-17 06:18:17","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72174","Ordinal":"1","Title":"fs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_","CVE":"CVE-2026-72174","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72174","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole()\n\nA PAGEMAP_SCAN ioctl requesting PM_SCAN_WP_MATCHING on a hugetlb VMA hangs\nthe calling thread, unkillably, as soon as the scan reaches an unpopulated\npart of the range:\n\n  do_pagemap_scan()\n    walk_page_range()\n      walk_hugetlb_range()\n        hugetlb_vma_lock_read()           # take the vma lock for read ...\n        pagemap_scan_pte_hole()           # ... ->pte_hole() for a hole\n          uffd_wp_range()\n            change_protection()\n              hugetlb_change_protection()\n                hugetlb_vma_lock_write()  # ... and block taking it for write\n\nwalk_hugetlb_range() holds the hugetlb vma lock for read across the whole\nwalk.  A present entry goes to ->hugetlb_entry(); an unpopulated one goes\nto ->pte_hole(), i.e.  pagemap_scan_pte_hole().  To write-protect the hole\nthat handler calls uffd_wp_range(), which on a hugetlb VMA reaches\nhugetlb_change_protection() and takes the same vma lock for write.  The\nthread then blocks in down_write() waiting for the read lock it is itself\nholding.\n\nThe populated path avoids this: pagemap_scan_hugetlb_entry()\nwrite-protects the entry inline under the page-table lock and never enters\nhugetlb_change_protection().\n\nDo the same for holes.  Fault in the page table and install the uffd-wp\nmarker directly with make_uffd_wp_huge_pte() under the page-table lock,\nrather than routing through uffd_wp_range().  That is the same sequence\nhugetlb_change_protection() runs for an unpopulated entry, minus the vma\nwrite lock -- which is safe to skip because PMD sharing is disabled on\nuffd-wp VMAs (hugetlb_unshare_all_pmds() runs at registration), leaving\nnothing for that lock to serialise against.","Type":"Description","Title":"fs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_"}]}}}