{
  "cveId": "CVE-2021-47637",
  "url": "https://patchblox.com/security/cve/CVE-2021-47637",
  "summary": "CVE-2021-47637 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47637, released February 26, 2025. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  ubifs: Fix deadlock in concurrent rename whiteou...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ubifs: Fix deadlock in concurrent rename whiteout and inode writeback  Following hung tasks: [   77.028764] task:kworker/u8:4    state:D stack:    0 pid:  132 [   77.028820] Call Trace: [   77.029027]  schedule\u002B0x8c/0x1b0 [   77.029067]  mutex_lock\u002B0x50/0x60 [   77.029074]  ubifs_write_inode\u002B0x68/0x1f0 [ubifs] [   77.029117]  __writeback_single_inode\u002B0x43c/0x570 [   77.029128]  writeback_sb_inodes\u002B0x259/0x740 [   77.029148]  wb_writeback\u002B0x107/0x4d0 [   77.029163]  wb_workfn\u002B0x162/0x7b0  [   92.390442] task:aa              state:D stack:    0 pid: 1506 [   92.390448] Call Trace: [   92.390458]  schedule\u002B0x8c/0x1b0 [   92.390461]  wb_wait_for_completion\u002B0x82/0xd0 [   92.390469]  __writeback_inodes_sb_nr\u002B0xb2/0x110 [   92.390472]  writeback_inodes_sb_nr\u002B0x14/0x20 [   92.390476]  ubifs_budget_space\u002B0x705/0xdd0 [ubifs] [   92.390503]  do_rename.cold\u002B0x7f/0x187 [ubifs] [   92.390549]  ubifs_rename\u002B0x8b/0x180 [ubifs] [   92.390571]  vfs_rename\u002B0xdb2/0x1170 [   92.390580]  do_renameat2\u002B0x554/0x770  , are caused by concurrent rename whiteout and inode writeback processes: \trename_whiteout(Thread 1)\t        wb_workfn(Thread2) ubifs_rename   do_rename     lock_4_inodes (Hold ui_mutex)     ubifs_budget_space       make_free_space         shrink_liability \t  __writeback_inodes_sb_nr \t    bdi_split_work_to_wbs (Queue new wb work) \t\t\t\t\t      wb_do_writeback(wb work) \t\t\t\t\t\t__writeback_single_inode \t\t\t\t\t          ubifs_write_inode \t\t\t\t\t            LOCK(ui_mutex) \t\t\t\t\t\t\t   \u2191 \t      wb_wait_for_completion (Wait wb work) \u003C-- deadlock!  Reproducer (Detail program in [Link]):   1. SYS_renameat2(\u0022/mp/dir/file\u0022, \u0022/mp/dir/whiteout\u0022, RENAME_WHITEOUT)   2. Consume out of space before kernel(mdelay) doing budget for whiteout  Fix it by doing whiteout space budget before locking ubifs inodes. BTW, it also fixes wrong goto tag \u0027out_release\u0027 in whiteout budget error handling path(It should at least recover dir i_size and unlock 4 ubifs inodes).",
  "published": "2025-02-26T06:37:05Z",
  "severity": "medium",
  "cvss": 5.5,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
  "epss": 0.00193,
  "epssPercentile": 0.08962,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.17.3-1",
      "fix": "DEBIAN-CVE-2021-47637",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47637",
      "released": "2025-02-26T06:37:05Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.17.3-1",
      "fix": "DEBIAN-CVE-2021-47637",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47637",
      "released": "2025-02-26T06:37:05Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.17.3-1",
      "fix": "DEBIAN-CVE-2021-47637",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47637",
      "released": "2025-02-26T06:37:05Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T19:12:23Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}