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        "name": "Kernel"
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  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80808.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: stop retrying saturated xattr cache entries\n\next4_xattr_block_set() retries when a cache entry selected for reuse\nhas a saturated reference count after taking the buffer lock. The retry\nreturns to the mbcache lookup without making that entry ineligible, so\nit can select the same unusable entry indefinitely. A task spinning\nthere can hold the parent directory's i_rwsem and leave concurrent\nrmdir callers blocked.\n\nNormally a reusable entry has a reference count below\nEXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are\nupdated under the same buffer lock. A corrupted filesystem can violate\nthat invariant. The syzbot reproducer reports allocator and xattr\ncorruption before triggering this retry loop.\n\nCheck the untrusted on-disk count before incrementing it, avoiding\noverflow, and clear MBE_REUSABLE_B when it is already saturated. The\nnext lookup then skips the entry that was just proven unusable. This\nmirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release\npath marks the entry reusable again on the exact 1024-to-1023\ntransition.\n\nUsing the same QEMU harness and guest parameters, current unpatched\nLinux hung in 6 of 8 420-second trials with the do_rmdir signature;\nrepresentative NMI backtraces caught the owner spinning in\next4_xattr_block_set(). The patched kernel completed 28 of 28 trials\nwithout a hung-task report; the final twelve trials exercised the\nreviewed overflow-safe form of the change. syzbot's patch testing also\ncompleted without reproducing the hang.",
  "id": "CVE-2026-80808",
  "modified": "2026-09-06T03:30:31.392652807Z",
  "published": "2026-09-04T15:13:28.562Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/119a2f053242ed75bdd2ebc95baf3ae7db6ccacf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/54b6bd40898de7906acb2bccc9a96d1b8e6b4323"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/61631352a5b405c89be579de00903b72e6888aa4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8865cd664484517703df5c18a965dc3227572b87"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/889ec86464d261f026f6c334040cfc6c58c99d58"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a40c45268f4358207aa9c53764fed2e05f62986a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dbd4aea175ad3c46436acb251e817b4374628072"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80808.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80808"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "ext4: stop retrying saturated xattr cache entries"
}