CVE-2026-80893 - Vulnerability Details

Vendors	Products
Linux	Linux Kernel

Link	Providers
https://git.kernel.org/stable/c/2b9a07002c2f296aa6a9c591213933d3492e3089
https://git.kernel.org/stable/c/2fa11c60c9c06bafc19cf4d9efdaa36a38079e87
https://git.kernel.org/stable/c/69cb5825d9988c7944bc9f1dc08cb233655405a7
https://git.kernel.org/stable/c/83abe2fd5b3aeb3123b5408a5a91709c5538fb23
https://git.kernel.org/stable/c/8b0de7005b148738d79d6c45594d566489948a68
https://git.kernel.org/stable/c/f1b1311c0352873137768bac5a126e491271a747

Type	Values Removed	Values Added
Weaknesses		CWE-119

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork() copy_hugetlb_page_range() clears the uffd-wp bit of migration and hwpoison entries with huge_pte_clear_uffd_wp(), which operates on the present-PTE bit position. Swap entries keep the uffd-wp state elsewhere -- the migration branch reads and sets it with pte_swp_uffd_wp() and pte_swp_mkuffd_wp() -- and the present-PTE position falls into the swap payload. On x86-64 it lands in the inverted swap offset, where a naturally-aligned hugetlb PFN always has the affected bit set, so the clear advances the encoded PFN by two pages. No userfaultfd needs to be involved: the clear is guarded only by the child VMA not being uffd-wp registered, so a plain fork() with an in-flight hugetlb migration entry (or a poisoned hugetlb page) corrupts the entry copied into the child. Instrumenting the clear and forking after MADV_HWPOISON on a 2MB anon hugetlb page shows: offset before=120e00 offset after =120e02 The fallout is mostly latent: rmap walks match migration entries by folio range and remove_migration_pte() rebuilds the PTE from the folio, so a within-folio PFN skew heals once migration completes. But any path that re-encodes the corrupted offset -- e.g. hugetlb_change_protection() rewriting a writable migration entry via make_readable_migration_entry(swp_offset(entry)) -- propagates it. Migration entries legitimately carry uffd-wp, so clear it with pte_swp_clear_uffd_wp(), matching copy_nonpresent_pte() and move_huge_pte(). A hwpoison entry, on the other hand, never carries the uffd-wp bit: it is installed fresh by make_hwpoison_entry() (try_to_unmap_one() does not preserve uffd-wp on the hwpoison path) and hugetlb_change_protection() leaves hwpoison entries untouched. There was nothing to clear there, only the corruption, so drop the clear entirely.
Title		mm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork()
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/2b9a07002c2f296aa6a9c591213933d3492e3089 https://git.kernel.org/stable/c/2fa11c60c9c06bafc19cf4d9efdaa36a38079e87 https://git.kernel.org/stable/c/69cb5825d9988c7944bc9f1dc08cb233655405a7 https://git.kernel.org/stable/c/83abe2fd5b3aeb3123b5408a5a91709c5538fb23 https://git.kernel.org/stable/c/8b0de7005b148738d79d6c45594d566489948a68 https://git.kernel.org/stable/c/f1b1311c0352873137768bac5a126e491271a747

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-80893", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.800Z", "datePublished": "2026-09-04T17:11:09.199Z", "dateUpdated": "2026-09-04T17:11:09.199Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-04T17:11:09.199Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork()\n\ncopy_hugetlb_page_range() clears the uffd-wp bit of migration and hwpoison\nentries with huge_pte_clear_uffd_wp(), which operates on the present-PTE\nbit position. Swap entries keep the uffd-wp state elsewhere -- the\nmigration branch reads and sets it with pte_swp_uffd_wp() and\npte_swp_mkuffd_wp() -- and the present-PTE position falls into the swap\npayload. On x86-64 it lands in the inverted swap offset, where a\nnaturally-aligned hugetlb PFN always has the affected bit set, so the\nclear advances the encoded PFN by two pages.\n\nNo userfaultfd needs to be involved: the clear is guarded only by the\nchild VMA not being uffd-wp registered, so a plain fork() with an\nin-flight hugetlb migration entry (or a poisoned hugetlb page) corrupts\nthe entry copied into the child. Instrumenting the clear and forking\nafter MADV_HWPOISON on a 2MB anon hugetlb page shows:\n\n offset before=120e00\n offset after =120e02\n\nThe fallout is mostly latent: rmap walks match migration entries by folio\nrange and remove_migration_pte() rebuilds the PTE from the folio, so a\nwithin-folio PFN skew heals once migration completes. But any path that\nre-encodes the corrupted offset -- e.g. hugetlb_change_protection()\nrewriting a writable migration entry via\nmake_readable_migration_entry(swp_offset(entry)) -- propagates it.\n\nMigration entries legitimately carry uffd-wp, so clear it with\npte_swp_clear_uffd_wp(), matching copy_nonpresent_pte() and\nmove_huge_pte().\n\nA hwpoison entry, on the other hand, never carries the uffd-wp bit: it is\ninstalled fresh by make_hwpoison_entry() (try_to_unmap_one() does not\npreserve uffd-wp on the hwpoison path) and hugetlb_change_protection()\nleaves hwpoison entries untouched. There was nothing to clear there, only\nthe corruption, so drop the clear entirely."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["mm/hugetlb.c"], "versions": [{"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "lessThan": "f1b1311c0352873137768bac5a126e491271a747", "status": "affected", "versionType": "git"}, {"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "lessThan": "69cb5825d9988c7944bc9f1dc08cb233655405a7", "status": "affected", "versionType": "git"}, {"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "lessThan": "8b0de7005b148738d79d6c45594d566489948a68", "status": "affected", "versionType": "git"}, {"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "lessThan": "2b9a07002c2f296aa6a9c591213933d3492e3089", "status": "affected", "versionType": "git"}, {"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "lessThan": "2fa11c60c9c06bafc19cf4d9efdaa36a38079e87", "status": "affected", "versionType": "git"}, {"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "lessThan": "83abe2fd5b3aeb3123b5408a5a91709c5538fb23", "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/hugetlb.c"], "versions": [{"version": "5.19", "status": "affected"}, {"version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.151", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.103", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "5.19", "versionEndExcluding": "6.1.183"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.151"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.103"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.18.44"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.1.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/f1b1311c0352873137768bac5a126e491271a747"}, {"url": "https://git.kernel.org/stable/c/69cb5825d9988c7944bc9f1dc08cb233655405a7"}, {"url": "https://git.kernel.org/stable/c/8b0de7005b148738d79d6c45594d566489948a68"}, {"url": "https://git.kernel.org/stable/c/2b9a07002c2f296aa6a9c591213933d3492e3089"}, {"url": "https://git.kernel.org/stable/c/2fa11c60c9c06bafc19cf4d9efdaa36a38079e87"}, {"url": "https://git.kernel.org/stable/c/83abe2fd5b3aeb3123b5408a5a91709c5538fb23"}], "title": "mm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["mm/hugetlb.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "f1b1311c0352873137768bac5a126e491271a747", "status": "affected", "version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "versionType": "git"}, {"lessThan": "69cb5825d9988c7944bc9f1dc08cb233655405a7", "status": "affected", "version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "versionType": "git"}, {"lessThan": "8b0de7005b148738d79d6c45594d566489948a68", "status": "affected", "version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "versionType": "git"}, {"lessThan": "2b9a07002c2f296aa6a9c591213933d3492e3089", "status": "affected", "version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "versionType": "git"}, {"lessThan": "2fa11c60c9c06bafc19cf4d9efdaa36a38079e87", "status": "affected", "version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "versionType": "git"}, {"lessThan": "83abe2fd5b3aeb3123b5408a5a91709c5538fb23", "status": "affected", "version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["mm/hugetlb.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.19"}, {"lessThan": "5.19", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.183", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.151", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.103", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.44", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork()\n\ncopy_hugetlb_page_range() clears the uffd-wp bit of migration and hwpoison\nentries with huge_pte_clear_uffd_wp(), which operates on the present-PTE\nbit position. Swap entries keep the uffd-wp state elsewhere -- the\nmigration branch reads and sets it with pte_swp_uffd_wp() and\npte_swp_mkuffd_wp() -- and the present-PTE position falls into the swap\npayload. On x86-64 it lands in the inverted swap offset, where a\nnaturally-aligned hugetlb PFN always has the affected bit set, so the\nclear advances the encoded PFN by two pages.\n\nNo userfaultfd needs to be involved: the clear is guarded only by the\nchild VMA not being uffd-wp registered, so a plain fork() with an\nin-flight hugetlb migration entry (or a poisoned hugetlb page) corrupts\nthe entry copied into the child. Instrumenting the clear and forking\nafter MADV_HWPOISON on a 2MB anon hugetlb page shows:\n\n offset before=120e00\n offset after =120e02\n\nThe fallout is mostly latent: rmap walks match migration entries by folio\nrange and remove_migration_pte() rebuilds the PTE from the folio, so a\nwithin-folio PFN skew heals once migration completes. But any path that\nre-encodes the corrupted offset -- e.g. hugetlb_change_protection()\nrewriting a writable migration entry via\nmake_readable_migration_entry(swp_offset(entry)) -- propagates it.\n\nMigration entries legitimately carry uffd-wp, so clear it with\npte_swp_clear_uffd_wp(), matching copy_nonpresent_pte() and\nmove_huge_pte().\n\nA hwpoison entry, on the other hand, never carries the uffd-wp bit: it is\ninstalled fresh by make_hwpoison_entry() (try_to_unmap_one() does not\npreserve uffd-wp on the hwpoison path) and hugetlb_change_protection()\nleaves hwpoison entries untouched. There was nothing to clear there, only\nthe corruption, so drop the clear entirely."}], "id": "CVE-2026-80893", "lastModified": "2026-09-04T18:17:57.467", "metrics": {}, "published": "2026-09-04T18:17:57.467", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2b9a07002c2f296aa6a9c591213933d3492e3089"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2fa11c60c9c06bafc19cf4d9efdaa36a38079e87"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/69cb5825d9988c7944bc9f1dc08cb233655405a7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/83abe2fd5b3aeb3123b5408a5a91709c5538fb23"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8b0de7005b148738d79d6c45594d566489948a68"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f1b1311c0352873137768bac5a126e491271a747"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

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