wifi: cfg80211: regulatory: improve invalid hints checking

{
  "id": "f48651adf13d3cc3abdf4298362faa08600e3de07eacf1114490af5c5b37e4a3",
  "url": "https://osv.dev/vulnerability/CVE-2025-21910",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "wifi: cfg80211: regulatory: improve invalid hints checking",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: wifi: cfg80211: regulatory: improve invalid hints checking Syzbot keeps reporting an issue [1] that occurs when erroneous symbols sent from userspace get through into user_alpha2[] via regulatory_hint_user() call. Such invalid regulatory hints should be rejected. While a sanity check from commit 47caf685a685 (\"cfg80211: regulatory: reject invalid hints\") looks to be enough to deter these very cases, there is a way to get around it due to 2 reasons. 1) The way isalpha() works, symbols other than latin lower and upper letters may be used to determine a country/domain. For instance, greek letters will also be considered upper/lower letters and for such characters isalpha() will return true as well. However, ISO-3166-1 alpha2 codes should only hold latin characters. 2) While processing a user regulatory request, between reg_process_hint_user() and regulatory_hint_user() there happens to be a call to queue_regulatory_request() which modifies letters in request->alpha2[] with toupper(). This works fine for latin symbols, less so for weird letter characters from the second part of _ctype[]. Syzbot triggers a warning in is_user_regdom_saved() by first sending over an unexpected non-latin letter that gets malformed by toupper() into a character that ends up failing isalpha() check. Prevent this by enhancing is_an_alpha2() to ensure that incoming symbols are latin letters and nothing else. [1] Syzbot report: ----------",
    "evidence": "osv:CVE-2025-21910",
    "products": [
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    "severity": "unknown",
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      "aliases": [
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      "modified": "2026-10-28T02:30:43.975618961Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/17aa34c84867f6cd181a5743e1c647e7766962a6",
        "https://git.kernel.org/stable/c/35ef07112b61b06eb30683a6563c9f6378c02476",
        "https://git.kernel.org/stable/c/59b348be7597c4a9903cb003c69e37df20c04a30",
        "https://git.kernel.org/stable/c/62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6",
        "https://git.kernel.org/stable/c/6a5e3b23054cee3b92683d1467e3fa83921f5622",
        "https://git.kernel.org/stable/c/be7c5f00aa7f1344293e4d48d0e12be83a2f223d",
        "https://git.kernel.org/stable/c/da3f599517ef2ea851208df3229d07728d238dc5",
        "https://git.kernel.org/stable/c/f4112cb477c727a65787a4065a75ca593bb5b2f4",
        "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html",
        "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21910.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-21910",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
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    "related_cves": [
      {
        "value": "CVE-2025-21910",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 511656,
  "published_at": "2025-04-01T15:40:49.189+00:00"
}