{"id":"CVE-2026-72203","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-72203","summary":"ntfs: skip extent mft records in writeback to prevent deadlock","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: skip extent mft records in writeback to prevent deadlock\n\nThis patch fixes the ABBA deadlock between extent_lock and extent\nmrec_lock triggered by xfstests generic/113, that occurs since the commit\n6994acf33bae (\"ntfs: use base mft_no when looking up base inode for\n\t\textent record\").\n\nPath A (inode writeback):\n  VFS writeback\n    -> ntfs_write_inode()\n      -> __ntfs_write_inode()\n        -> mutex_lock(&ni->extent_lock)\n        -> mutex_lock(&tni->mrec_lock)\n\nPath B (MFT folio writeback):\n  VFS writeback of $MFT dirty folios\n    -> ntfs_mft_writepages()\n      -> ntfs_write_mft_block()\n        -> ntfs_may_write_mft_record()\n          -> holds one extent mrec_lock from a previous iteration\n          -> tries to acquire another base inode extent_lock\n\nBy removing all extent_lock and extent mrec_lock acquisition from the MFT\nfolio writeback path, the ABBA lock ordering is eliminated:\n\nPath A: __ntfs_write_inode(): extent_lock -> mrec_lock\nPath B (removed): ntfs_write_mft_block(): mrec_lock -> extent_lock\n\nPath B is always redundant for extent records because:\n\n1. mark_mft_record_dirty(ext_ni) does NOT dirty the MFT folio.\n   It only sets NInoDirty(ext_ni) and marks the base VFS inode dirty\n   via __mark_inode_dirty(I_DIRTY_DATASYNC), which triggers Path A.\n   Therefore, normal extent modifications never create a situation where\n   the MFT folio is dirty and Path B is not scheduled.\n\n2. The MFT folio only gets dirtied via ntfs_mft_mark_dirty() inside\n   ntfs_mft_record_alloc(). But all identified callers in attrib.c\n   (ntfs_attr_add, ntfs_attr_record_move_away,\n   ntfs_attr_make_non_resident, ntfs_attr_record_resize) follow through\n   with mark_mft_record_dirty(), which triggers Path A to write the\n   complete record.\n\n3. ntfs_evict_big_inode() calls ntfs_commit_inode() before freeing extent\n   inodes, ensuring all dirty extents are flushed via Path A before the\n   base inode leaves the icache.","published":"2026-08-15T05:54:00.321Z","modified":"2026-08-16T03:48:37.495639030Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"7.1.5"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/76bc14c7097ff678b2b5dbfd4fa33b46897d87ce"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f831ab09d521898bf1dd99bf5adfd630ea1428e3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72203.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72203"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-16T03:48:37.495639030Z"}}