KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()

{
  "id": "4c75c1e4e749807db4af6d071bb31a944db631bc20e16ddb866af8452616a15d",
  "url": "https://osv.dev/vulnerability/CVE-2026-98638",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve() pkvm_vcpu_init_sve() clamps only the upper bound of the host-provided sve_max_vl, so an invalid vector length reaches sve_state_size_from_vl() and the WARN_ON() there, which is fatal at EL2. The existing !sve_state_size test rejects such a length, but only after the macro has run. Check sve_vl_valid() before deriving the state size. A valid length cannot yield a zero size, so the !sve_state_size test goes with it.",
    "evidence": "osv:CVE-2026-98638",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98638",
      "aliases": [
        "CVE-2026-98638"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "5db1bef933427aa467ad89c7b695a84a6b4afe16"
                },
                {
                  "fixed": "faf66e55e87498ab4bf88cdf9a629e61b3f2d3bc"
                },
                {
                  "fixed": "bae3e4493046de4fefa15f809d9b8dc114e84a3d"
                },
                {
                  "fixed": "2a2eb10795a1e495aebc7f829ccecb72c05b4fd9"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98638.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.16.0"
                },
                {
                  "fixed": "6.18.55"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.9"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98638.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:53.009695126Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2a2eb10795a1e495aebc7f829ccecb72c05b4fd9",
        "https://git.kernel.org/stable/c/bae3e4493046de4fefa15f809d9b8dc114e84a3d",
        "https://git.kernel.org/stable/c/faf66e55e87498ab4bf88cdf9a629e61b3f2d3bc",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98638.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98638",
        "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/2026/98xxx/CVE-2026-98638.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98638",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 521906,
  "published_at": "2026-10-18T15:20:09.38+00:00"
}