{"id":"CVE-2026-89646","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89646","summary":"ceph: fix leaked inode reference on writeback abort at umount","details":"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.","published":"2026-09-11T19:45:37.767Z","modified":"2026-09-14T03:46:22.019585635Z","cvss":{"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"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.18.50"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/ac7a5a5385762df458d10cccc086a4e079be7409"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c25aee9c630fb86f98d79eccb75765067079b972"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ec32015a955c5d326c5e26610edfdcccd52f2314"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89646.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89646"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:22.019585635Z"}}