{
  "cveId": "CVE-2021-46989",
  "url": "https://patchblox.com/security/cve/CVE-2021-46989",
  "summary": "CVE-2021-46989 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-46989, released February 28, 2024. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  hfsplus: prevent corruption in shrinking truncat...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  hfsplus: prevent corruption in shrinking truncate  I believe there are some issues introduced by commit 31651c607151 (\u0022hfsplus: avoid deadlock on file truncation\u0022)  HFS\u002B has extent records which always contains 8 extents.  In case the first extent record in catalog file gets full, new ones are allocated from extents overflow file.  In case shrinking truncate happens to middle of an extent record which locates in extents overflow file, the logic in hfsplus_file_truncate() was changed so that call to hfs_brec_remove() is not guarded any more.  Right action would be just freeing the extents that exceed the new size inside extent record by calling hfsplus_free_extents(), and then check if the whole extent record should be removed.  However since the guard (blk_cnt \u003E start) is now after the call to hfs_brec_remove(), this has unfortunate effect that the last matching extent record is removed unconditionally.  To reproduce this issue, create a file which has at least 10 extents, and then perform shrinking truncate into middle of the last extent record, so that the number of remaining extents is not under or divisible by 8.  This causes the last extent record (8 extents) to be removed totally instead of truncating into middle of it.  Thus this causes corruption, and lost data.  Fix for this is simply checking if the new truncated end is below the start of this extent record, making it safe to remove the full extent record.  However call to hfs_brec_remove() can\u0027t be moved to it\u0027s previous place since we\u0027re dropping -\u003Etree_lock and it can cause a race condition and the cached info being invalidated possibly corrupting the node data.  Another issue is related to this one.  When entering into the block (blk_cnt \u003E start) we are not holding the -\u003Etree_lock.  We break out from the loop not holding the lock, but hfs_find_exit() does unlock it.  Not sure if it\u0027s possible for someone else to take the lock under our feet, but it can cause hard to debug errors and premature unlocking.  Even if there\u0027s no real risk of it, the locking should still always be kept in balance.  Thus taking the lock now just before the check.",
  "published": "2024-02-28T09:15:37Z",
  "severity": "high",
  "cvss": 7.1,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
  "epss": 0.00242,
  "epssPercentile": 0.155,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.10.38-1",
      "fix": "DEBIAN-CVE-2021-46989",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-46989",
      "released": "2024-02-28T09:15:37Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.10.38-1",
      "fix": "DEBIAN-CVE-2021-46989",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-46989",
      "released": "2024-02-28T09:15:37Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.10.38-1",
      "fix": "DEBIAN-CVE-2021-46989",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-46989",
      "released": "2024-02-28T09:15:37Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}