ipc: drop the mqueue mount with kern_unmount() on setup failure

{
  "id": "915097765cddc62a848cd067b7001ba8e7b64465342b263608d0060586e67282",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-99172",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ipc: drop the mqueue mount with kern_unmount() on setup failure",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ipc: drop the mqueue mount with kern_unmount() on setup failure mq_init_ns() creates the mqueue mount with fc_mount_longterm(), so its ->mnt_ns is MNT_NS_INTERNAL. When setting up the mqueue or ipc sysctls or msg_init_ns() fails afterwards, create_ipc_ns() drops it with a plain mntput(). With ->mnt_ns set that takes the fast path of mntput_no_expire(). The count drops to zero and nothing ever kills the mount, so the mount and the mqueue superblock are leaked. Commit dc55e35f9e81 (\"ipc: Store mqueue sysctls in the ipc namespace\") added the first failure path after mq_init_ns() and never dropped the mount. Commit 7229d74e5e8c (\"ipc: create_ipc_ns: drop mqueue mount on sysctl setup failure\") tried to fix that with a mntput() but that doesn't help for a long-term mount. Use kern_unmount(). free_ipc() open-codes the same thing for a namespace that made it.",
    "evidence": "cve:CVE-2026-99172",
    "products": [
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/1/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-99172",
      "aliases": [
        "CVE-2026-99172"
      ],
      "metrics": [],
      "affected": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "dc55e35f9e810f23dd69cfdc91a3d636023f57a2",
              "lessThan": "c0620b648321fff654173d238d4a85298ea16d05",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "dc55e35f9e810f23dd69cfdc91a3d636023f57a2",
              "lessThan": "f0e48172a59e517e613b73f73cc35f24fd123aeb",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "ipc/namespace.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.19"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "5.19",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.2.13",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "ipc/namespace.c"
          ],
          "defaultStatus": "affected"
        }
      ],
      "modified": "2026-10-28T10:35:27.245Z",
      "provider": "cve",
      "references": [
        "https://git.kernel.org/stable/c/c0620b648321fff654173d238d4a85298ea16d05",
        "https://git.kernel.org/stable/c/f0e48172a59e517e613b73f73cc35f24fd123aeb"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "shortName": "Linux",
          "dateUpdated": "2026-10-28T10:35:27.245Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-99172",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 425362,
  "published_at": "2026-10-28T10:35:27.245+00:00"
}