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CVE-2026-72203 (GCVE-0-2026-72203)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-19 07:37
VLAI
Title
ntfs: skip extent mft records in writeback to prevent deadlock
Summary
In the Linux kernel, the following vulnerability has been resolved: ntfs: skip extent mft records in writeback to prevent deadlock This patch fixes the ABBA deadlock between extent_lock and extent mrec_lock triggered by xfstests generic/113, that occurs since the commit 6994acf33bae ("ntfs: use base mft_no when looking up base inode for extent record"). Path A (inode writeback): VFS writeback -> ntfs_write_inode() -> __ntfs_write_inode() -> mutex_lock(&ni->extent_lock) -> mutex_lock(&tni->mrec_lock) Path B (MFT folio writeback): VFS writeback of $MFT dirty folios -> ntfs_mft_writepages() -> ntfs_write_mft_block() -> ntfs_may_write_mft_record() -> holds one extent mrec_lock from a previous iteration -> tries to acquire another base inode extent_lock By removing all extent_lock and extent mrec_lock acquisition from the MFT folio writeback path, the ABBA lock ordering is eliminated: Path A: __ntfs_write_inode(): extent_lock -> mrec_lock Path B (removed): ntfs_write_mft_block(): mrec_lock -> extent_lock Path B is always redundant for extent records because: 1. mark_mft_record_dirty(ext_ni) does NOT dirty the MFT folio. It only sets NInoDirty(ext_ni) and marks the base VFS inode dirty via __mark_inode_dirty(I_DIRTY_DATASYNC), which triggers Path A. Therefore, normal extent modifications never create a situation where the MFT folio is dirty and Path B is not scheduled. 2. The MFT folio only gets dirtied via ntfs_mft_mark_dirty() inside ntfs_mft_record_alloc(). But all identified callers in attrib.c (ntfs_attr_add, ntfs_attr_record_move_away, ntfs_attr_make_non_resident, ntfs_attr_record_resize) follow through with mark_mft_record_dirty(), which triggers Path A to write the complete record. 3. ntfs_evict_big_inode() calls ntfs_commit_inode() before freeing extent inodes, ensuring all dirty extents are flushed via Path A before the base inode leaves the icache.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7ffa8f3d30236e0ab897c30bdb01224ff1fe1c89 (git)
Affected: 1e9ea7e04472d4e5e12e58c881eaacfb3e49b669 , < f831ab09d521898bf1dd99bf5adfd630ea1428e3 (git)
Affected: 1e9ea7e04472d4e5e12e58c881eaacfb3e49b669 , < 76bc14c7097ff678b2b5dbfd4fa33b46897d87ce (git)
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Linux Linux Affected: 2.6.12
Affected: 7.1
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.9 , < 7.1 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
  "containers": {
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/mft.c"
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              "versionType": "original_commit_for_fix"
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                  "versionEndExcluding": "6.9",
                  "versionStartIncluding": "2.6.12",
                  "vulnerable": true
                },
                {
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              "operator": "OR"
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      "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    -\u003e ntfs_write_inode()\n      -\u003e __ntfs_write_inode()\n        -\u003e mutex_lock(\u0026ni-\u003eextent_lock)\n        -\u003e mutex_lock(\u0026tni-\u003emrec_lock)\n\nPath B (MFT folio writeback):\n  VFS writeback of $MFT dirty folios\n    -\u003e ntfs_mft_writepages()\n      -\u003e ntfs_write_mft_block()\n        -\u003e ntfs_may_write_mft_record()\n          -\u003e holds one extent mrec_lock from a previous iteration\n          -\u003e 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 -\u003e mrec_lock\nPath B (removed): ntfs_write_mft_block(): mrec_lock -\u003e 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."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
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              "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."
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        "shortName": "Linux"
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        {
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      "title": "ntfs: skip extent mft records in writeback to prevent deadlock",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72203",
    "datePublished": "2026-08-15T05:54:00.321Z",
    "dateReserved": "2026-08-09T03:40:39.912Z",
    "dateUpdated": "2026-08-19T07:37:27.158Z",
    "state": "PUBLISHED"
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    },
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      "cve": "CVE-2026-72203",
      "id": "msrc_CVE-2026-72203",
      "initial_release_date": "2026-08-23T14:42:59.000Z",
      "product_status:known_affected": "1",
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      "version": "1"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-18T11:08:27+00:00",
      "cve": "CVE-2026-72203",
      "id": "CVE-2026-72203",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ntfs: skip extent mft records in writeback to prevent deadlock",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72203.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-21T00:42:35Z",
      "cve": "CVE-2026-72203",
      "id": "CVE-2026-72203",
      "initial_release_date": "2026-08-21T00:42:35Z",
      "product_status:known_affected": "255",
      "product_status:known_not_affected": "29",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72203",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72203.json",
      "version": "2"
    }
  }
}



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Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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