nbd: fix race between nbd_alloc_config() and module removal

{
  "id": "77e9eb1256dd37a132d32b9d4507dee8c2a5a64eef647c962a597c6f354177f4",
  "url": "https://osv.dev/vulnerability/CVE-2022-49300",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "nbd: fix race between nbd_alloc_config() and module removal",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: nbd: fix race between nbd_alloc_config() and module removal When nbd module is being removing, nbd_alloc_config() may be called concurrently by nbd_genl_connect(), although try_module_get() will return false, but nbd_alloc_config() doesn't handle it. The race may lead to the leak of nbd_config and its related resources (e.g, recv_workq) and oops in nbd_read_stat() due to the unload of nbd module as shown below: BUG: kernel NULL pointer dereference, address: 0000000000000040 Oops: 0000 [#1] SMP PTI CPU: 5 PID: 13840 Comm: kworker/u17:33 Not tainted 5.14.0+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Workqueue: knbd16-recv recv_work [nbd] RIP: 0010:nbd_read_stat.cold+0x130/0x1a4 [nbd] Call Trace: recv_work+0x3b/0xb0 [nbd] process_one_work+0x1ed/0x390 worker_thread+0x4a/0x3d0 kthread+0x12a/0x150 ret_from_fork+0x22/0x30 Fixing it by checking the return value of try_module_get() in nbd_alloc_config(). As nbd_alloc_config() may return ERR_PTR(-ENODEV), assign nbd->config only when nbd_alloc_config() succeeds to ensure the value of nbd->config is binary (valid or NULL). Also adding a debug message to check the reference counter of nbd_config during module removal.",
    "evidence": "osv:CVE-2022-49300",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
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        "prerequisites": [],
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    "severity": "medium",
    "structured": {
      "id": "CVE-2022-49300",
      "aliases": [
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"
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      "modified": "2026-10-28T02:30:52.776426646Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/122e4adaff2439f1cc18cc7e931980fa7560df5c",
        "https://git.kernel.org/stable/c/165cf2e0019fa6cedc75b456490c41494c34abb4",
        "https://git.kernel.org/stable/c/2573f2375b64280be977431701ed5d33b75b9ad0",
        "https://git.kernel.org/stable/c/2888fa41985f93ed0a6837cfbb06bcbfd7fa2314",
        "https://git.kernel.org/stable/c/71c142f910da44421213ade601bcbd23ceae19fa",
        "https://git.kernel.org/stable/c/8a7da4ced236ce6637fe70f14ca18e718d4bf9e9",
        "https://git.kernel.org/stable/c/c55b2b983b0fa012942c3eb16384b2b722caa810",
        "https://git.kernel.org/stable/c/d09525720dd5201756f698bee1076de9aefd4602",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49300.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-49300",
        "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-2022-49300.json"
      }
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        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 521505,
  "published_at": "2025-02-26T02:10:35.594+00:00"
}