ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()

{
  "id": "84735669b7ad24e7264e6e452685b511c6297260d524e1c63f821bdd43415663",
  "url": "https://osv.dev/vulnerability/CVE-2022-49889",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters() On some machines the number of listed CPUs may be bigger than the actual CPUs that exist. The tracing subsystem allocates a per_cpu directory with access to the per CPU ring buffer via a cpuX file. But to save space, the ring buffer will only allocate buffers for online CPUs, even though the CPU array will be as big as the nr_cpu_ids. With the addition of waking waiters on the ring buffer when closing the file, the ring_buffer_wake_waiters() now needs to make sure that the buffer is allocated (with the irq_work allocated with it) before trying to wake waiters, as it will cause a NULL pointer dereference. While debugging this, I added a NULL check for the buffer itself (which is OK to do), and also NULL pointer checks against buffer->buffers (which is not fine, and will WARN) as well as making sure the CPU number passed in is within the nr_cpu_ids (which is also not fine if it isn't). Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705",
    "evidence": "osv:CVE-2022-49889",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.78",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.0.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2022-49889",
      "aliases": [
        "CVE-2022-49889"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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                  "fixed": "49ca992f6e50d0f46ec9608f44e011cf3121f389"
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            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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                  "introduced": "5.19.17"
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                  "fixed": "5.20"
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          "versions": [
            "v5.15.77",
            "v5.15.76",
            "v5.15.75",
            "v6.0.7",
            "v6.0.6",
            "v6.0.5",
            "v6.0.4",
            "v6.0.3",
            "v5.19.17"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49889.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.15.75"
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                {
                  "fixed": "5.15.78"
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              ]
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.0.3"
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                {
                  "fixed": "6.0.8"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49889.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:48.090711812Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/49ca992f6e50d0f46ec9608f44e011cf3121f389",
        "https://git.kernel.org/stable/c/7433632c9ff68a991bd0bc38cabf354e9d2de410",
        "https://git.kernel.org/stable/c/b5074df412bf3df9d6ce096b6fa03eb1082d05c9",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49889.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-49889",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49889.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2022-49889",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 515862,
  "published_at": "2025-05-01T14:10:33.832+00:00"
}