mshv: Fix race in mshv_irqfd_deassign

{
  "id": "1919db906452b24640e968454675e4e344afb928dbaa834e9a1eff20c22934e7",
  "url": "https://osv.dev/vulnerability/CVE-2026-80896",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mshv: Fix race in mshv_irqfd_deassign",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: mshv: Fix race in mshv_irqfd_deassign mshv_irqfd_deactivate() and the hlist traversal of pt_irqfds_list require pt->pt_irqfds_lock to be held, but mshv_irqfd_deassign() omits it. This races with the EPOLLHUP path in mshv_irqfd_wakeup(), which does take the lock before calling mshv_irqfd_deactivate(). Additionally, mshv_irqfd_deactivate() uses hlist_del() which poisons the node pointers rather than resetting them. Since mshv_irqfd_is_active() relies on hlist_unhashed() (checks pprev == NULL), a poisoned node still appears active. If a concurrent path calls mshv_irqfd_deactivate() again on the same irqfd, the guard fails to prevent a double hlist_del() on poisoned pointers. Fix both issues: - Add the missing spin_lock_irq/spin_unlock_irq around the list traversal in mshv_irqfd_deassign(), matching mshv_irqfd_release(). - Use hlist_del_init() instead of hlist_del() so the node is properly marked as unhashed after removal, making the is_active guard reliable.",
    "evidence": "osv:CVE-2026-80896",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.44",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-80896",
      "aliases": [
        "CVE-2026-80896"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "621191d709b14882270dfd8ea5d7d6cdfebe2c35"
                },
                {
                  "fixed": "72a90ce4918b5a2d4820fe20677ba9af780d8826"
                },
                {
                  "fixed": "4529a41a675b96e0f876eef1cc93a31a57cb4d18"
                },
                {
                  "fixed": "0762262ac3e70f65b3bb843fe892f8bac1562d08"
                }
              ]
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80896.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.15.0"
                },
                {
                  "fixed": "6.18.44"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80896.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:22.697277451Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0762262ac3e70f65b3bb843fe892f8bac1562d08",
        "https://git.kernel.org/stable/c/4529a41a675b96e0f876eef1cc93a31a57cb4d18",
        "https://git.kernel.org/stable/c/72a90ce4918b5a2d4820fe20677ba9af780d8826",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80896.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-80896",
        "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/2026/80xxx/CVE-2026-80896.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-80896",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 489226,
  "published_at": "2026-09-04T17:11:11.689+00:00"
}