vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex

{
  "id": "2a40209e06f7710b1b7b49172363eaf1a2a30fd15d6e16795c675360b9323539",
  "url": "https://osv.dev/vulnerability/CVE-2026-46036",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex vfio_cdx_set_msi_trigger() reads vdev->config_msi and operates on the vdev->cdx_irqs array based on its value, but provides no serialization against concurrent VFIO_DEVICE_SET_IRQS ioctls. Two callers can race such that one observes config_msi as set while another clears it and frees cdx_irqs via vfio_cdx_msi_disable(), resulting in a use-after-free of the cdx_irqs array. Add a cdx_irqs_lock mutex to struct vfio_cdx_device and acquire it in vfio_cdx_set_msi_trigger(), which is the single chokepoint through which all updates to config_msi, cdx_irqs, and msi_count flow, covering both the ioctl path and the close-device cleanup path. This keeps the test of config_msi atomic with the subsequent enable, disable, or trigger operations. Drop the pre-call !cdx_irqs test from vfio_cdx_irqs_cleanup() as part of this change: the optimization it provided is redundant with the !config_msi early-return inside vfio_cdx_msi_disable(), and leaving the test in place would be an unsynchronized read of state the new lock is meant to protect.",
    "evidence": "osv:CVE-2026-46036",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.86",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.27",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-46036",
      "aliases": [
        "CVE-2026-46036"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "848e447e000c41894ff931dc7c004fd42c8840f8"
                },
                {
                  "fixed": "ddf96e23c366c566283fce8377928851fa7f5e81"
                },
                {
                  "fixed": "7b436ade16cc81095d79b79f8efa3af0a4f5c5a2"
                },
                {
                  "fixed": "7530f34ec0ca1438d45a75dcb43183a1cc92eced"
                },
                {
                  "fixed": "670e8864b1a218d72f08db40d0103adf38fa1d9b"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46036.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.12.86"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.27"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46036.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.267975957Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/670e8864b1a218d72f08db40d0103adf38fa1d9b",
        "https://git.kernel.org/stable/c/7530f34ec0ca1438d45a75dcb43183a1cc92eced",
        "https://git.kernel.org/stable/c/7b436ade16cc81095d79b79f8efa3af0a4f5c5a2",
        "https://git.kernel.org/stable/c/ddf96e23c366c566283fce8377928851fa7f5e81",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46036.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46036",
        "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/2026/46xxx/CVE-2026-46036.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46036",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 509771,
  "published_at": "2026-05-27T12:56:46.381+00:00"
}