{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72203", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.912Z", "datePublished": "2026-08-15T05:54:00.321Z", "dateUpdated": "2026-08-18T06:56:21.384Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-18T06:56:21.384Z" }, "descriptions": [ { "lang": "en", "value": "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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The ABBA deadlock is reachable through concurrent VFS writeback on an rw-mounted NTFS volume; ntfs registers ntfs_export_ops, so nfsd/ksmbd remote WRITE/CLOSE/fsync RPCs on an exported NTFS share hit __ntfs_write_inode() and ntfs_mft_writepages() the same as local aio/write syscalls.\nAC:L - xfstests generic/113 (aio-stress with concurrent O_DIRECT/O_SYNC writes) reliably reproduces the hang; an attacker controls both lock-order participants by issuing parallel file metadata writes and sync/writeback pressure without races or attacker-independent memory layout.\nPR:N - Exploitation needs only write access to an rw-mounted or NFS/SMB-exported NTFS volume to drive ntfs_mft_record_alloc and concurrent writeback; no CAP_SYS_ADMIN, root, or init-namespace privileges on the server are required to deadlock the writeback paths.\nUI:N - Once an NTFS volume is rw-mounted (dual-boot partition, removable media, loop mount, or network export), the attacker issues the concurrent writes itself; no additional victim clicks, opens, or cooperative actions are required beyond that standing configuration.\nS:U - The circular mutex wait between extent_lock and extent mrec_lock only hangs kernel writeback and I/O worker threads within the host kernel security authority; it does not cross VM, container, IOMMU, or other security-boundary scopes.\nC:N - This is a deterministic lock-order inversion with no out-of-bounds access, use-after-free, or information disclosure; blocked threads wait on mutexes without reading attacker-controlled freed memory or leaking kernel pointers.\nI:N - The defect prevents completion of metadata writeback by deadlocking mutex acquisition; it does not perform attacker-controlled memory writes, corrupt on-disk NTFS structures, or provide a metadata modification primitive beyond denying forward progress.\nA:H - The ABBA deadlock between inode writeback (extent_lock then extent mrec_lock) and $MFT folio writeback (held mrec_lock then extent_lock) hangs kworker writeback and sync/fsync callers indefinitely, causing system-wide I/O denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ntfs/mft.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "f831ab09d521898bf1dd99bf5adfd630ea1428e3", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "76bc14c7097ff678b2b5dbfd4fa33b46897d87ce", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ntfs/mft.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "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": "2.6.12", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f831ab09d521898bf1dd99bf5adfd630ea1428e3" }, { "url": "https://git.kernel.org/stable/c/76bc14c7097ff678b2b5dbfd4fa33b46897d87ce" } ], "title": "ntfs: skip extent mft records in writeback to prevent deadlock", "x_generator": { "engine": "bippy-1.2.0" } } } }