{"api_version":"1","generated_at":"2026-10-27T06:52:21+00:00","cve":"CVE-2026-89646","urls":{"html":"https://cve.report/CVE-2026-89646","api":"https://cve.report/api/cve/CVE-2026-89646.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89646","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89646"},"summary":{"title":"ceph: fix leaked inode reference on writeback abort at umount","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix leaked inode reference on writeback abort at umount\n\nceph_dirty_folio() takes a wrbuffer claim on each newly dirtied folio: it\nbumps i_wrbuffer_ref (taking an ihold() on the 0->1 transition) and\nattaches the snap_context to folio->private.  That claim is released only\nby ceph_put_wrbuffer_cap_refs(), which for a submitted write runs from\nwritepages_finish().\n\nIn ceph_submit_write(), if ceph_inc_osd_stopping_blocker() fails -- which\nhappens during umount -- the request is aborted before submission: the\nalready-collected folios are only redirtied and unlocked, so\nwritepages_finish() never runs and the claim is leaked.\nredirty_page_for_writepage() -> folio_redirty_for_writepage() ->\nfilemap_dirty_folio() sets PG_dirty directly and does not go through\n->dirty_folio, so ceph_dirty_folio() is not re-entered to rebalance it.\nBecause every subsequent writeback also fails the osd_stopping_blocker,\ni_wrbuffer_ref never returns to 0, the ihold() is never dropped, and the\ninode cannot be evicted:\n\n  VFS: Busy inodes after unmount of ceph\n  kernel BUG at fs/super.c:650!\n\nRelease the orphaned claim in the abort path before redirtying, via\nceph_undo_wrbuffer_claim(): detach the snap_context, drop the wrbuffer\nreference (letting i_wrbuffer_ref reach 0 and iput() the inode), and drop\nthe snap_context reference -- i.e. do what writepages_finish() would have\ndone for these never-submitted folios.\n\nOnly the locked_pages entries are undone; folios still in the fbatch were\nnever dirty-cleared by this call (folio_clear_dirty_for_io() is the\nownership-transfer point, and a successful move NULLs the fbatch slot), so\nthey hold no claim this call owns.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:50","updated_at":"2026-10-19 09:18:01"},"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/ec32015a955c5d326c5e26610edfdcccd52f2314","name":"https://git.kernel.org/stable/c/ec32015a955c5d326c5e26610edfdcccd52f2314","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c25aee9c630fb86f98d79eccb75765067079b972","name":"https://git.kernel.org/stable/c/c25aee9c630fb86f98d79eccb75765067079b972","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ac7a5a5385762df458d10cccc086a4e079be7409","name":"https://git.kernel.org/stable/c/ac7a5a5385762df458d10cccc086a4e079be7409","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89646","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89646","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fd7449d937e7fb3144770592927cf452bf66dbd3 ec32015a955c5d326c5e26610edfdcccd52f2314 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fd7449d937e7fb3144770592927cf452bf66dbd3 ac7a5a5385762df458d10cccc086a4e079be7409 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fd7449d937e7fb3144770592927cf452bf66dbd3 c25aee9c630fb86f98d79eccb75765067079b972 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"89646","cve":"CVE-2026-89646","epss":"0.001730000","percentile":"0.069510000","score_date":"2026-09-14","updated_at":"2026-09-15 00:00:42"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/ceph/addr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"ec32015a955c5d326c5e26610edfdcccd52f2314","status":"affected","version":"fd7449d937e7fb3144770592927cf452bf66dbd3","versionType":"git"},{"lessThan":"ac7a5a5385762df458d10cccc086a4e079be7409","status":"affected","version":"fd7449d937e7fb3144770592927cf452bf66dbd3","versionType":"git"},{"lessThan":"c25aee9c630fb86f98d79eccb75765067079b972","status":"affected","version":"fd7449d937e7fb3144770592927cf452bf66dbd3","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/ceph/addr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.15"},{"lessThan":"6.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.15","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix leaked inode reference on writeback abort at umount\n\nceph_dirty_folio() takes a wrbuffer claim on each newly dirtied folio: it\nbumps i_wrbuffer_ref (taking an ihold() on the 0->1 transition) and\nattaches the snap_context to folio->private.  That claim is released only\nby ceph_put_wrbuffer_cap_refs(), which for a submitted write runs from\nwritepages_finish().\n\nIn ceph_submit_write(), if ceph_inc_osd_stopping_blocker() fails -- which\nhappens during umount -- the request is aborted before submission: the\nalready-collected folios are only redirtied and unlocked, so\nwritepages_finish() never runs and the claim is leaked.\nredirty_page_for_writepage() -> folio_redirty_for_writepage() ->\nfilemap_dirty_folio() sets PG_dirty directly and does not go through\n->dirty_folio, so ceph_dirty_folio() is not re-entered to rebalance it.\nBecause every subsequent writeback also fails the osd_stopping_blocker,\ni_wrbuffer_ref never returns to 0, the ihold() is never dropped, and the\ninode cannot be evicted:\n\n  VFS: Busy inodes after unmount of ceph\n  kernel BUG at fs/super.c:650!\n\nRelease the orphaned claim in the abort path before redirtying, via\nceph_undo_wrbuffer_claim(): detach the snap_context, drop the wrbuffer\nreference (letting i_wrbuffer_ref reach 0 and iput() the inode), and drop\nthe snap_context reference -- i.e. do what writepages_finish() would have\ndone for these never-submitted folios.\n\nOnly the locked_pages entries are undone; folios still in the fbatch were\nnever dirty-cleared by this call (folio_clear_dirty_for_io() is the\nownership-transfer point, and a successful move NULLs the fbatch slot), so\nthey hold no claim this call owns."}],"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 leak is in ceph_submit_write() from ceph_writepages_start() during local VFS writeback on umount (ceph_kill_sb → sync_filesystem → do_writepages), not MDS/OSD message handlers. fs/ceph is a kernel client with no network-facing server listener.\nAC:L - Dirtying pages then unmounting drives both sides: ceph_kill_sb waits at most mount_timeout (default 60s) or a killable signal, then sets STOPPING_FLUSHING while writepages_start still holds a blocker and locked folios, so the abort is reached reliably without an uncontrolled race.\nPR:L - An unprivileged user with write access to an already-mounted CephFS can dirty pages; container/pod teardown, autofs, or systemd performs the umount. CephFS lacks FS_USERNS_MOUNT, but the attacker does not need CAP_SYS_ADMIN themselves.\nUI:N - The attacker dirties files and can trigger or wait for unmount via pod exit, autofs idle unmount, or their own umount; no separate victim action such as opening a file or mounting the filesystem is required.\nS:U - The leaked inode references and subsequent superblock teardown affect only the host kernel's VFS/Ceph client state within the same security authority; this is not a VM escape, IOMMU bypass, or sandbox escape.\nC:H - The leaked ihold pins inodes through generic_shutdown_super so the superblock and ceph_fs_client are destroyed while those inodes remain. Later writeback or iput on the leftover mapping is a use-after-free of the freed superblock, scored High per UAF guidance.\nI:H - Inodes that survive umount retain address_spaces and pointers into destroyed ceph_fs_client/mdsc state. Subsequent iput_final/writeback operate on freed objects and poisoned i_op/s_op, a UAF write and control-flow primitive scored High.\nA:H - Unmount reports \"VFS: Busy inodes after unmount of ceph\" and hits CHECK_DATA_CORRUPTION in generic_shutdown_super (BUG() with CONFIG_BUG_ON_DATA_CORRUPTION), and VFS_PTR_POISON on surviving inodes guarantees a later oops or panic."}]}],"providerMetadata":{"dateUpdated":"2026-10-19T08:50:17.976Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/ec32015a955c5d326c5e26610edfdcccd52f2314"},{"url":"https://git.kernel.org/stable/c/ac7a5a5385762df458d10cccc086a4e079be7409"},{"url":"https://git.kernel.org/stable/c/c25aee9c630fb86f98d79eccb75765067079b972"}],"title":"ceph: fix leaked inode reference on writeback abort at umount","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89646","datePublished":"2026-09-11T19:45:37.767Z","dateReserved":"2026-09-11T19:38:34.741Z","dateUpdated":"2026-10-19T08:50:17.976Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:50","lastModifiedDate":"2026-10-19 09:18:01","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":"89646","Ordinal":"1","Title":"ceph: fix leaked inode reference on writeback abort at umount","CVE":"CVE-2026-89646","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89646","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix leaked inode reference on writeback abort at umount\n\nceph_dirty_folio() takes a wrbuffer claim on each newly dirtied folio: it\nbumps i_wrbuffer_ref (taking an ihold() on the 0->1 transition) and\nattaches the snap_context to folio->private.  That claim is released only\nby ceph_put_wrbuffer_cap_refs(), which for a submitted write runs from\nwritepages_finish().\n\nIn ceph_submit_write(), if ceph_inc_osd_stopping_blocker() fails -- which\nhappens during umount -- the request is aborted before submission: the\nalready-collected folios are only redirtied and unlocked, so\nwritepages_finish() never runs and the claim is leaked.\nredirty_page_for_writepage() -> folio_redirty_for_writepage() ->\nfilemap_dirty_folio() sets PG_dirty directly and does not go through\n->dirty_folio, so ceph_dirty_folio() is not re-entered to rebalance it.\nBecause every subsequent writeback also fails the osd_stopping_blocker,\ni_wrbuffer_ref never returns to 0, the ihold() is never dropped, and the\ninode cannot be evicted:\n\n  VFS: Busy inodes after unmount of ceph\n  kernel BUG at fs/super.c:650!\n\nRelease the orphaned claim in the abort path before redirtying, via\nceph_undo_wrbuffer_claim(): detach the snap_context, drop the wrbuffer\nreference (letting i_wrbuffer_ref reach 0 and iput() the inode), and drop\nthe snap_context reference -- i.e. do what writepages_finish() would have\ndone for these never-submitted folios.\n\nOnly the locked_pages entries are undone; folios still in the fbatch were\nnever dirty-cleared by this call (folio_clear_dirty_for_io() is the\nownership-transfer point, and a successful move NULLs the fbatch slot), so\nthey hold no claim this call owns.","Type":"Description","Title":"ceph: fix leaked inode reference on writeback abort at umount"}]}}}