KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped

{
  "id": "31a3d696714f76ea1d196a844152c735abee4adf1d55a28cf3ed3233b9a20278",
  "url": "https://osv.dev/vulnerability/CVE-2026-90040",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Forcefully invalidate SNP VMSA if its backing gmem page is zapped Wire up a gmem_invalidate_range() call for SNP VMs, and use it to force vCPUs to reload/recheck their guest-provided VMSA if the backing gmem page is being invalidated, e.g. is being PUNCH_HOLE'd. Use the same core logic to handle invalidations as VMX does for the APIC-access page, as the two concepts are nearly identical: shove the physical address of a page into the vCPU's control structure: 1. Snapshot the invalidation sequence counter 2. Grab the pfn (from guest_memfd in this case) 3. Acquire mmu_lock for read 4. Re-request reload if retry is needed, otherwise commit the change. Note, the re-request action in #4 is necessary as KVM's retry logic is fuzzy, i.e. can get false positives. If the guest_memfd page has been dropped, at some point a subsequent reload will fail to get a PFN from guest_memfd, and KVM will fail KVM_RUN. If the retry was due to a false positive, KVM will retry until there are no relevant MMU notifier events (and will retry in the \"outer\" loop, i.e. will drop locks and resched as needed). Note #2! Take care to invalidate the VMSA when a relevant memslot is DELETED or MOVED, as invalidations in response to PUNCH_HOLE are predicated on memslot bindings (KVM doesn't know what GFN range(s) to invalidate without a binding). And more importantly, the VMSA mapping requires a memslot, i.e. must be invalidated if its m",
    "evidence": "osv:CVE-2026-90040",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.57",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-90040",
      "aliases": [
        "CVE-2026-90040"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "e366f92ea99e1961fbad5e2110900e9f4fcb249b"
                },
                {
                  "fixed": "ef4dee4640c6adc3051401399b0788135e77d50b"
                },
                {
                  "fixed": "2640cc26ed0dd1bf6ec2f6852a60e494093db3e5"
                },
                {
                  "fixed": "d1a3c216233413f57f5341a9b878b7e2dde7e785"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90040.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.11.0"
                },
                {
                  "fixed": "6.18.57"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90040.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:35.372350146Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2640cc26ed0dd1bf6ec2f6852a60e494093db3e5",
        "https://git.kernel.org/stable/c/d1a3c216233413f57f5341a9b878b7e2dde7e785",
        "https://git.kernel.org/stable/c/ef4dee4640c6adc3051401399b0788135e77d50b",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90040.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-90040",
        "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/2026/90xxx/CVE-2026-90040.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-90040",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 502953,
  "published_at": "2026-09-16T10:33:38.79+00:00"
}