inet: frags: flush pending skbs in fqdir_pre_exit()

{
  "id": "b71e18f17db511ffac84b81f9aa4e3ce21be5942541fbfa1b23eaee06d903b56",
  "url": "https://osv.dev/vulnerability/CVE-2025-68768",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "inet: frags: flush pending skbs in fqdir_pre_exit()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: inet: frags: flush pending skbs in fqdir_pre_exit() We have been seeing occasional deadlocks on pernet_ops_rwsem since September in NIPA. The stuck task was usually modprobe (often loading a driver like ipvlan), trying to take the lock as a Writer. lockdep does not track readers for rwsems so the read wasn't obvious from the reports. On closer inspection the Reader holding the lock was conntrack looping forever in nf_conntrack_cleanup_net_list(). Based on past experience with occasional NIPA crashes I looked thru the tests which run before the crash and noticed that the crash follows ip_defrag.sh. An immediate red flag. Scouring thru (de)fragmentation queues reveals skbs sitting around, holding conntrack references. The problem is that since conntrack depends on nf_defrag_ipv6, nf_defrag_ipv6 will load first. Since nf_defrag_ipv6 loads first its netns exit hooks run _after_ conntrack's netns exit hook. Flush all fragment queue SKBs during fqdir_pre_exit() to release conntrack references before conntrack cleanup runs. Also flush the queues in timer expiry handlers when they discover fqdir->dead is set, in case packet sneaks in while we're running the pre_exit flush. The commit under Fixes is not exactly the culprit, but I think previously the timer firing would eventually unblock the spinning conntrack.",
    "evidence": "osv:CVE-2025-68768",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.143",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.93",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-68768",
      "aliases": [
        "CVE-2025-68768"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "d5dd88794a13c2f24cce31abad7a0a6c5e0ed2db"
                },
                {
                  "fixed": "22ee4010866da81aeee08e1ea3fddbe418feb212"
                },
                {
                  "fixed": "543555954b1ee8d1903a7020324efb41b0c97428"
                },
                {
                  "fixed": "c70df25214ac9b32b53e18e6ae3b8f073ffa6903"
                },
                {
                  "fixed": "006a5035b495dec008805df249f92c22c89c3d2e"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68768.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.3.0"
                },
                {
                  "fixed": "6.6.143"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.93"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68768.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.729266290Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/006a5035b495dec008805df249f92c22c89c3d2e",
        "https://git.kernel.org/stable/c/22ee4010866da81aeee08e1ea3fddbe418feb212",
        "https://git.kernel.org/stable/c/543555954b1ee8d1903a7020324efb41b0c97428",
        "https://git.kernel.org/stable/c/c70df25214ac9b32b53e18e6ae3b8f073ffa6903",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68768.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-68768",
        "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/2025/68xxx/CVE-2025-68768.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-68768",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 519453,
  "published_at": "2026-01-13T15:28:47.106+00:00"
}