{"api_version":"1","generated_at":"2026-09-20T00:50:08+00:00","cve":"CVE-2026-89836","urls":{"html":"https://cve.report/CVE-2026-89836","api":"https://cve.report/api/cve/CVE-2026-89836.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89836","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89836"},"summary":{"title":"f2fs: fix folio_nr_pages() race after put in large folio invalidate","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix folio_nr_pages() race after put in large folio invalidate\n\nOur v6.18 based Android system is continuely suffering livelock and bad\npage stat as shown in[1] which related to broken xarray slot status. By\ninvestigating big folio operations within f2fs, we find below races and\nfix it by get the nr_pages before drop the refcount and folio_lock.\n\nf2fs_get_read_data_folio() calls f2fs_folio_put() before\nfolio_nr_pages() when invalidating a large folio from the page cache.\nThat unlocks the folio and drops the caller reference, leaving a window\nwhere a concurrent truncate or folio split can shrink the compound folio\nor free it before the invalidate range is computed. An undersized range\nthen leaves split sub-folios in mapping->i_pages, which can later\ninteract badly with truncate and reclaim (stale xarray entries and bad\npage state when folio->mapping no longer matches the mapping being\ntruncated).\n\n[1]\nPID: 2594     TASK: ffffff8169b81580  CPU: 7    COMMAND: \"Thread-3\"\n #0 [ffffffc08ef2b8a0] xas_load at ffffffe52d1f42a4\n #1 [ffffffc08ef2b900] find_get_entries at ffffffe52c185798\n #2 [ffffffc08ef2bb60] truncate_inode_pages_range at ffffffe52c19e83c\n #3 [ffffffc08ef2bbc0] truncate_inode_pages_final at ffffffe52c19ec2c\n #4 [ffffffc08ef2bc20] f2fs_evict_inode at ffffffe52c4c8400\n #5 [ffffffc08ef2bcc0] evict at ffffffe52c2de9f4\n #6 [ffffffc08ef2bd00] iput at ffffffe52c2db1b4\n #7 [ffffffc08ef2bd30] dentry_unlink_inode at ffffffe52c2d7204\n #8 [ffffffc08ef2bd50] __dentry_kill at ffffffe52c2d3dcc\n #9 [ffffffc08ef2bd80] dput at ffffffe52c2d3c3c\n #10 [ffffffc08ef2bda0] __fput at ffffffe52c2b0a7c\n #11 [ffffffc08ef2bde0] ____fput at ffffffe52c2b1034\n #12 [ffffffc08ef2bdf0] task_work_run at ffffffe52beea200\n #13 [ffffffc08ef2be20] exit_to_user_mode_loop at ffffffe52bfbc17c\n #14 [ffffffc08ef2be80] el0_svc at ffffffe52d1f8e54\n #15 [ffffffc08ef2beb0] el0t_64_sync_handler at ffffffe52d1f8d10","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-16 11:16:50","updated_at":"2026-09-16 15:18:12"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/cc34df18da92f68f9b384c3ae95ad64be46cb5ee","name":"https://git.kernel.org/stable/c/cc34df18da92f68f9b384c3ae95ad64be46cb5ee","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0dab71381f1b4d12dc2056f8bd5aaa9d93ce9082","name":"https://git.kernel.org/stable/c/0dab71381f1b4d12dc2056f8bd5aaa9d93ce9082","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89836","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89836","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 05e65c14ea59a401cec4284e9d612f9d5dc1b3f8 cc34df18da92f68f9b384c3ae95ad64be46cb5ee git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 05e65c14ea59a401cec4284e9d612f9d5dc1b3f8 0dab71381f1b4d12dc2056f8bd5aaa9d93ce9082 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.5 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/f2fs/data.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"cc34df18da92f68f9b384c3ae95ad64be46cb5ee","status":"affected","version":"05e65c14ea59a401cec4284e9d612f9d5dc1b3f8","versionType":"git"},{"lessThan":"0dab71381f1b4d12dc2056f8bd5aaa9d93ce9082","status":"affected","version":"05e65c14ea59a401cec4284e9d612f9d5dc1b3f8","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/f2fs/data.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.0"},{"lessThan":"7.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.5","versionStartIncluding":"7.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"7.0","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix folio_nr_pages() race after put in large folio invalidate\n\nOur v6.18 based Android system is continuely suffering livelock and bad\npage stat as shown in[1] which related to broken xarray slot status. By\ninvestigating big folio operations within f2fs, we find below races and\nfix it by get the nr_pages before drop the refcount and folio_lock.\n\nf2fs_get_read_data_folio() calls f2fs_folio_put() before\nfolio_nr_pages() when invalidating a large folio from the page cache.\nThat unlocks the folio and drops the caller reference, leaving a window\nwhere a concurrent truncate or folio split can shrink the compound folio\nor free it before the invalidate range is computed. An undersized range\nthen leaves split sub-folios in mapping->i_pages, which can later\ninteract badly with truncate and reclaim (stale xarray entries and bad\npage state when folio->mapping no longer matches the mapping being\ntruncated).\n\n[1]\nPID: 2594     TASK: ffffff8169b81580  CPU: 7    COMMAND: \"Thread-3\"\n #0 [ffffffc08ef2b8a0] xas_load at ffffffe52d1f42a4\n #1 [ffffffc08ef2b900] find_get_entries at ffffffe52c185798\n #2 [ffffffc08ef2bb60] truncate_inode_pages_range at ffffffe52c19e83c\n #3 [ffffffc08ef2bbc0] truncate_inode_pages_final at ffffffe52c19ec2c\n #4 [ffffffc08ef2bc20] f2fs_evict_inode at ffffffe52c4c8400\n #5 [ffffffc08ef2bcc0] evict at ffffffe52c2de9f4\n #6 [ffffffc08ef2bd00] iput at ffffffe52c2db1b4\n #7 [ffffffc08ef2bd30] dentry_unlink_inode at ffffffe52c2d7204\n #8 [ffffffc08ef2bd50] __dentry_kill at ffffffe52c2d3dcc\n #9 [ffffffc08ef2bd80] dput at ffffffe52c2d3c3c\n #10 [ffffffc08ef2bda0] __fput at ffffffe52c2b0a7c\n #11 [ffffffc08ef2bde0] ____fput at ffffffe52c2b1034\n #12 [ffffffc08ef2bdf0] task_work_run at ffffffe52beea200\n #13 [ffffffc08ef2be20] exit_to_user_mode_loop at ffffffe52bfbc17c\n #14 [ffffffc08ef2be80] el0_svc at ffffffe52d1f8e54\n #15 [ffffffc08ef2beb0] el0t_64_sync_handler at ffffffe52d1f8d10"}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The bug is in f2fs_get_read_data_folio() on a locally mounted f2fs volume, reached when GC or other f2fs helpers grab a single-page folio while a large folio is cached. f2fs is the Android/embedded userdata filesystem; the path is local syscalls, not a network protocol.\nAC:L - The attacker drives both sides of the race: one thread keeps large folios cached and forces GC via writes into f2fs_balance_fs, while concurrent threads split or reclaim those folios with posix_fadvise(DONTNEED), madvise, or memory pressure in the window after f2fs_folio_put() and before folio_nr_pages().\nPR:L - CAP_LINUX_IMMUTABLE is needed only to set the flag, but Android f2fs /data already has immutable/fsverity files with large folios. An unprivileged app can read them, write its own data to trigger GC without CAP_SYS_ADMIN, and race reclaim; the GC ioctl is optional.\nUI:N - The attacker can populate large folios, force GC, and race folio split or reclaim with their own processes; no separate victim action is required.\nS:U - Page-cache xarray corruption and folio use-after-free stay inside the host kernel; this is local privilege escalation, not a VM, IOMMU, or sandbox boundary crossing.\nC:H - After the put, folio_nr_pages() may run on a split or already-freed folio, and an undersized invalidate leaves stale i_pages xarray entries. That page-cache UAF allows a reused folio to be read as another mapping's pages, enabling kernel memory disclosure.\nI:H - Stale mapping->i_pages slots and UAF of compound-folio metadata are heap and page-cache corruption. Reused folios and later truncate or reclaim against the wrong mapping yield write primitives and control-flow hijacking, not only a crash.\nA:H - The reported failure is livelock and bad page state in truncate_inode_pages_range (xas_load/find_get_entries) during inode eviction, i.e. a kernel oops, BUG, or hang with complete loss of availability."}]}],"providerMetadata":{"dateUpdated":"2026-09-16T14:39:08.158Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/cc34df18da92f68f9b384c3ae95ad64be46cb5ee"},{"url":"https://git.kernel.org/stable/c/0dab71381f1b4d12dc2056f8bd5aaa9d93ce9082"}],"title":"f2fs: fix folio_nr_pages() race after put in large folio invalidate","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89836","datePublished":"2026-09-16T10:31:10.233Z","dateReserved":"2026-09-11T19:38:34.769Z","dateUpdated":"2026-09-16T14:39:08.158Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-16 11:16:50","lastModifiedDate":"2026-09-16 15:18:12","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89836","Ordinal":"1","Title":"f2fs: fix folio_nr_pages() race after put in large folio invalid","CVE":"CVE-2026-89836","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89836","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix folio_nr_pages() race after put in large folio invalidate\n\nOur v6.18 based Android system is continuely suffering livelock and bad\npage stat as shown in[1] which related to broken xarray slot status. By\ninvestigating big folio operations within f2fs, we find below races and\nfix it by get the nr_pages before drop the refcount and folio_lock.\n\nf2fs_get_read_data_folio() calls f2fs_folio_put() before\nfolio_nr_pages() when invalidating a large folio from the page cache.\nThat unlocks the folio and drops the caller reference, leaving a window\nwhere a concurrent truncate or folio split can shrink the compound folio\nor free it before the invalidate range is computed. An undersized range\nthen leaves split sub-folios in mapping->i_pages, which can later\ninteract badly with truncate and reclaim (stale xarray entries and bad\npage state when folio->mapping no longer matches the mapping being\ntruncated).\n\n[1]\nPID: 2594     TASK: ffffff8169b81580  CPU: 7    COMMAND: \"Thread-3\"\n #0 [ffffffc08ef2b8a0] xas_load at ffffffe52d1f42a4\n #1 [ffffffc08ef2b900] find_get_entries at ffffffe52c185798\n #2 [ffffffc08ef2bb60] truncate_inode_pages_range at ffffffe52c19e83c\n #3 [ffffffc08ef2bbc0] truncate_inode_pages_final at ffffffe52c19ec2c\n #4 [ffffffc08ef2bc20] f2fs_evict_inode at ffffffe52c4c8400\n #5 [ffffffc08ef2bcc0] evict at ffffffe52c2de9f4\n #6 [ffffffc08ef2bd00] iput at ffffffe52c2db1b4\n #7 [ffffffc08ef2bd30] dentry_unlink_inode at ffffffe52c2d7204\n #8 [ffffffc08ef2bd50] __dentry_kill at ffffffe52c2d3dcc\n #9 [ffffffc08ef2bd80] dput at ffffffe52c2d3c3c\n #10 [ffffffc08ef2bda0] __fput at ffffffe52c2b0a7c\n #11 [ffffffc08ef2bde0] ____fput at ffffffe52c2b1034\n #12 [ffffffc08ef2bdf0] task_work_run at ffffffe52beea200\n #13 [ffffffc08ef2be20] exit_to_user_mode_loop at ffffffe52bfbc17c\n #14 [ffffffc08ef2be80] el0_svc at ffffffe52d1f8e54\n #15 [ffffffc08ef2beb0] el0t_64_sync_handler at ffffffe52d1f8d10","Type":"Description","Title":"f2fs: fix folio_nr_pages() race after put in large folio invalid"}]}}}