net/l2tp: fix warning in l2tp_exit_net found by syzbot

{
  "id": "e54cc37a59f0dce236df1ccbcbc207604abc802b5f7dde6ef9fb540b018ad3ec",
  "url": "https://osv.dev/vulnerability/CVE-2024-53211",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/l2tp: fix warning in l2tp_exit_net found by syzbot",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/l2tp: fix warning in l2tp_exit_net found by syzbot In l2tp's net exit handler, we check that an IDR is empty before destroying it: WARN_ON_ONCE(!idr_is_empty(&pn->l2tp_tunnel_idr)); idr_destroy(&pn->l2tp_tunnel_idr); By forcing memory allocation failures in idr_alloc_32, syzbot is able to provoke a condition where idr_is_empty returns false despite there being no items in the IDR. This turns out to be because the radix tree of the IDR contains only internal radix-tree nodes and it is this that causes idr_is_empty to return false. The internal nodes are cleaned by idr_destroy. Use idr_for_each to check that the IDR is empty instead of idr_is_empty to avoid the problem.",
    "evidence": "osv:CVE-2024-53211",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.2",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2024-53211",
      "aliases": [
        "CVE-2024-53211"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "73d33bd063c4cfef3db17f9bec3d202928ed8631"
                },
                {
                  "fixed": "a487cc8986d6dd75b60b59004f3bd2ea9b4dd541"
                },
                {
                  "fixed": "5d066766c5f1252f98ff859265bcd1a5b52ac46c"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-53211.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.12.0"
                },
                {
                  "fixed": "6.12.2"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-53211.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:39.032433051Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5d066766c5f1252f98ff859265bcd1a5b52ac46c",
        "https://git.kernel.org/stable/c/a487cc8986d6dd75b60b59004f3bd2ea9b4dd541",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/53xxx/CVE-2024-53211.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-53211",
        "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/2024/53xxx/CVE-2024-53211.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-53211",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 506456,
  "published_at": "2024-12-27T13:49:57.169+00:00"
}