FKIE_CVE-2026-97985

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-09-25 11:17
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
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0630bfc773d85ac44da05b2c5a037dbbd39301ab
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/94fd4debd2e3a69cf93e766c8b328a810c228119
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f1816b3d7ce80dcf086bb68ff5ae6e09520ca1fa
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fc62a26493a98a0424d9dae2eb92a1daa1321f65
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/unix/af_unix.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0630bfc773d85ac44da05b2c5a037dbbd39301ab",
              "status": "affected",
              "version": "22dd70eb2c3d754862964377a75abafd3167346b",
              "versionType": "git"
            },
            {
              "lessThan": "f1816b3d7ce80dcf086bb68ff5ae6e09520ca1fa",
              "status": "affected",
              "version": "22dd70eb2c3d754862964377a75abafd3167346b",
              "versionType": "git"
            },
            {
              "lessThan": "fc62a26493a98a0424d9dae2eb92a1daa1321f65",
              "status": "affected",
              "version": "22dd70eb2c3d754862964377a75abafd3167346b",
              "versionType": "git"
            },
            {
              "lessThan": "94fd4debd2e3a69cf93e766c8b328a810c228119",
              "status": "affected",
              "version": "22dd70eb2c3d754862964377a75abafd3167346b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ae3f9e1221b31b18dbd4c4b85d08574996bbd973",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ba0db4638525b8b054b3d546b45f7e473f477027",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "022d81a709cd553bbe2db8675f8e824f4aee6284",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "16dc252e7007547a7b72a2c21022ef81fb45e6a3",
              "versionType": "git"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.157",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.88",
              "versionType": "semver"
            },
            {
              "lessThan": "6.7",
              "status": "affected",
              "version": "6.6.29",
              "versionType": "semver"
            },
            {
              "lessThan": "6.9",
              "status": "affected",
              "version": "6.8.8",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/unix/af_unix.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "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."
    }
  ],
  "id": "CVE-2026-97985",
  "lastModified": "2026-09-25T11:17:26.560",
  "metrics": {},
  "published": "2026-09-25T11:17:26.560",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0630bfc773d85ac44da05b2c5a037dbbd39301ab"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/94fd4debd2e3a69cf93e766c8b328a810c228119"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f1816b3d7ce80dcf086bb68ff5ae6e09520ca1fa"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fc62a26493a98a0424d9dae2eb92a1daa1321f65"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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