CVE-2026-97985 (GCVE-0-2026-97985)
Vulnerability from cvelistv5
Published
2026-09-25 10:23
Modified
2026-10-21 12:53
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: af_unix: Update last skb marker in manage_oob(). Fahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU due to OOB skb. In the following cases, manage_oob() skips OOB skb(s) and returns NULL for the last recv(MSG_PEEK): socketpair(AF_UNIX, SOCK_STREAM, 0, sk); 1) skb -> OOB skb -> NULL send(sk[0], "ab", 2, MSG_OOB); recv(sk[1], buf, 0, MSG_PEEK); 2) skb -> consumed OOB skb -> NULL send(sk[0], "ab", 2, MSG_OOB); recv(sk[1], buf, 1, MSG_OOB); recv(sk[1], buf, 0, MSG_PEEK); 3) consumed OOB skb -> OOB skb -> NULL send(sk[0], "a", 1, MSG_OOB); recv(sk[1], buf, 0, MSG_OOB); send(sk[0], "b", 1, MSG_OOB); recv(sk[1], buf, 1, MSG_PEEK); Then, @copied is 0 in unix_stream_read_generic() (zero-length buffer, or non-OOB skb is not yet consumed), and unix_stream_data_wait() is called. However, it returns immediately because @last is not updated in unix_stream_read_generic(), and the thread busy-waits for a new skb. Let's update @last in manage_oob(). For MSG_PEEK, @last is updated with the skipped OOB, and for the non-peek case, @last matches the returned value (when !copied) because OOB is unlinked. Note that manage_oob() is inlined and no stack canary is added.
References
Impacted products
Vendor Product Version
Linux Linux Version: 022d81a709cd553bbe2db8675f8e824f4aee6284
Version: 22dd70eb2c3d754862964377a75abafd3167346b
Version: 22dd70eb2c3d754862964377a75abafd3167346b
Version: 22dd70eb2c3d754862964377a75abafd3167346b
Version: 22dd70eb2c3d754862964377a75abafd3167346b
Version: ae3f9e1221b31b18dbd4c4b85d08574996bbd973
Version: ba0db4638525b8b054b3d546b45f7e473f477027
Version: 16dc252e7007547a7b72a2c21022ef81fb45e6a3
Version: 6.6.29   ≤
Version: 5.15.157   ≤
Version: 6.1.88   ≤
Version: 6.8.8   ≤
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Update last skb marker in manage_oob().\n\nFahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU\ndue to OOB skb.\n\nIn the following cases, manage_oob() skips OOB skb(s) and returns\nNULL for the last recv(MSG_PEEK):\n\n  socketpair(AF_UNIX, SOCK_STREAM, 0, sk);\n\n  1) skb -\u003e OOB skb -\u003e NULL\n     send(sk[0], \"ab\", 2, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_PEEK);\n\n  2) skb -\u003e consumed OOB skb -\u003e NULL\n     send(sk[0], \"ab\", 2, MSG_OOB);\n     recv(sk[1], buf, 1, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_PEEK);\n\n  3) consumed OOB skb -\u003e OOB skb -\u003e NULL\n     send(sk[0], \"a\", 1, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_OOB);\n     send(sk[0], \"b\", 1, MSG_OOB);\n     recv(sk[1], buf, 1, MSG_PEEK);\n\nThen, @copied is 0 in unix_stream_read_generic() (zero-length buffer,\nor non-OOB skb is not yet consumed), and unix_stream_data_wait() is\ncalled.\n\nHowever, it returns immediately because @last is not updated in\nunix_stream_read_generic(), and the thread busy-waits for a new skb.\n\nLet\u0027s update @last in manage_oob().\n\nFor MSG_PEEK, @last is updated with the skipped OOB, and for the\nnon-peek case, @last matches the returned value (when !copied)\nbecause OOB is unlinked.\n\nNote that manage_oob() is inlined and no stack canary is added."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:53:57.548Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/bd91dc313afe21e9d6b31ca6a47606a33ca5e35c"
        },
        {
          "url": "https://git.kernel.org/stable/c/0630bfc773d85ac44da05b2c5a037dbbd39301ab"
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        {
          "url": "https://git.kernel.org/stable/c/f1816b3d7ce80dcf086bb68ff5ae6e09520ca1fa"
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        {
          "url": "https://git.kernel.org/stable/c/fc62a26493a98a0424d9dae2eb92a1daa1321f65"
        },
        {
          "url": "https://git.kernel.org/stable/c/94fd4debd2e3a69cf93e766c8b328a810c228119"
        }
      ],
      "title": "af_unix: Update last skb marker in manage_oob().",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97985",
    "datePublished": "2026-09-25T10:23:20.173Z",
    "dateReserved": "2026-09-25T10:18:58.208Z",
    "dateUpdated": "2026-10-21T12:53:57.548Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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