6lowpan: fix NHC entry use-after-free on error path

{
  "id": "53ffd8d0019edaf99fd55d713283c2ad4570c0864dacd64360d9fa97904d78ef",
  "url": "https://osv.dev/vulnerability/CVE-2026-64452",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "6lowpan: fix NHC entry use-after-free on error path",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: 6lowpan: fix NHC entry use-after-free on error path lowpan_nhc_do_uncompression() looks up an NHC descriptor while holding lowpan_nhc_lock. If the descriptor has no uncompress callback, the error path drops the lock before printing nhc->name. lowpan_nhc_del() removes descriptors under the same lock and then relies on synchronize_net() before the owning module can be unloaded. That only waits for net RX RCU readers. lowpan_header_decompress() is also exported and can be reached from callers that are not necessarily covered by the net core RX critical section, for example the Bluetooth 6LoWPAN L2CAP receive path. This leaves a race where one task drops lowpan_nhc_lock in the error path, another task unregisters and frees the matching descriptor after synchronize_net() returns, and the first task then dereferences nhc->name for the warning. With the post-unlock window widened, KASAN reports: BUG: KASAN: slab-use-after-free in lowpan_nhc_do_uncompression+0x1f4/0x220 Read of size 8 lowpan_nhc_do_uncompression lowpan_header_decompress Fix this by printing the warning before dropping lowpan_nhc_lock, so the descriptor name is read while unregister is still excluded. The malformed packet is still rejected with -ENOTSUPP.",
    "evidence": "osv:CVE-2026-64452",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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            "value": "6.12.96",
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            "value": "6.18.39",
            "evidence": "/affected/1/ranges"
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            "value": "7.1.4",
            "evidence": "/affected/1/ranges"
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    "severity": "high",
    "structured": {
      "id": "CVE-2026-64452",
      "aliases": [
        "CVE-2026-64452"
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H"
        }
      ],
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      "modified": "2026-10-28T02:30:44.310471704Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0beccbcf50de125be5520d0ffc59af4bb8655482",
        "https://git.kernel.org/stable/c/1720db928e5a58ca7d75ac1d514c3b73fd7061a7",
        "https://git.kernel.org/stable/c/593b78bb3c7ef0c6e9ae6fdf5afa80a5f7573168",
        "https://git.kernel.org/stable/c/80b5c8779acee0550845394fb3e5176a398aa24c",
        "https://git.kernel.org/stable/c/9c2f5c0829a8c8b904dae36be6d8056b719ac605",
        "https://git.kernel.org/stable/c/a8e3a94711134e898c6021a6b77374efa91b3639",
        "https://git.kernel.org/stable/c/b713aa0cc344f10f7a9928a230b5f5e780d04078",
        "https://git.kernel.org/stable/c/cc27aea4d454abfb385ee2c9499c78b96db9b728",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64452.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64452",
        "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/2026/64xxx/CVE-2026-64452.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64452",
        "evidence": "/id"
      }
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 512404,
  "published_at": "2026-07-25T08:51:21.754+00:00"
}