wifi: mac80211: Fix static_branch_dec() underflow for aql_disable.

{
  "id": "c57ab24793d0399b0e9060708c8b5481f2255e573bb6bad65c5c8df9168c4626",
  "url": "https://osv.dev/vulnerability/CVE-2026-31551",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "wifi: mac80211: Fix static_branch_dec() underflow for aql_disable.",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: Fix static_branch_dec() underflow for aql_disable. syzbot reported static_branch_dec() underflow in aql_enable_write(). [0] The problem is that aql_enable_write() does not serialise concurrent write()s to the debugfs. aql_enable_write() checks static_key_false(&aql_disable.key) and later calls static_branch_inc() or static_branch_dec(), but the state may change between the two calls. aql_disable does not need to track inc/dec. Let's use static_branch_enable() and static_branch_disable(). [0]: val == 0 WARNING: kernel/jump_label.c:311 at __static_key_slow_dec_cpuslocked.part.0+0x107/0x120 kernel/jump_label.c:311, CPU#0: syz.1.3155/20288 Modules linked in: CPU: 0 UID: 0 PID: 20288 Comm: syz.1.3155 Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 RIP: 0010:__static_key_slow_dec_cpuslocked.part.0+0x107/0x120 kernel/jump_label.c:311 Code: f2 c9 ff 5b 5d c3 cc cc cc cc e8 54 f2 c9 ff 48 89 df e8 ac f9 ff ff eb ad e8 45 f2 c9 ff 90 0f 0b 90 eb a2 e8 3a f2 c9 ff 90 <0f> 0b 90 eb 97 48 89 df e8 5c 4b 33 00 e9 36 ff ff ff 0f 1f 80 00 RSP: 0018:ffffc9000b9f7c10 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffffffff9b3e5d40 RCX: ffffffff823c57b4 RDX: ffff8880285a0000 RSI: ffffffff823c5846 RDI: ffff8880285a0000 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 000000000000",
    "evidence": "osv:CVE-2026-31551",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "evidence": "/affected/1/ranges"
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        "affected_versions": []
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    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-31551",
      "aliases": [
        "CVE-2026-31551"
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      "modified": "2026-10-28T02:30:26.251388381Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/256f7d4c11235d0569f78413c41dc89d2dc1557c",
        "https://git.kernel.org/stable/c/29a1a350afcd28a2150bd73b8bd83eac3480f13e",
        "https://git.kernel.org/stable/c/5ba05436f15d16ae7ab04b880e8bf8d440be892b",
        "https://git.kernel.org/stable/c/787152497ac763deab16f6f4b7ce79aaeb3eb7e8",
        "https://git.kernel.org/stable/c/8bb90ff77326c34e75b573b1febdd9586fec5aba",
        "https://git.kernel.org/stable/c/b24763d32d5b4ada766deca4b42d6766272fef0c",
        "https://git.kernel.org/stable/c/b94ae8e0d5fe1bdbbfdc3854ff6ce98f6876a828",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31551.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-31551",
        "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/2026/31xxx/CVE-2026-31551.json"
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    },
    "related_cves": [
      {
        "value": "CVE-2026-31551",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 492703,
  "published_at": "2026-04-24T14:33:18.23+00:00"
}