bpf: Reject non-negative offsets in stack_slot_obj_get_spi()

{
  "id": "3518aff04bea50a5f58db115742b7510634f3dda69ec17b3fcbd0fa3a3188723",
  "url": "https://osv.dev/vulnerability/CVE-2026-98599",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: Reject non-negative offsets in stack_slot_obj_get_spi()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: Reject non-negative offsets in stack_slot_obj_get_spi() bpf_get_spi() computes (-off - 1) / BPF_REG_SIZE using C division, which truncates toward zero. For off == 0, this produces spi 0, the same index used by the valid stack slot at fp-8. stack_slot_obj_get_spi() currently checks alignment and the resulting spi bounds, but does not reject the non-negative offset itself. It can therefore validate a PTR_TO_STACK register holding fp+0 against an iterator stored at fp-8 even though the runtime receives the actual fp+0 pointer. An effectful iterator kfunc can then interpret memory outside the BPF stack as iterator state. Reject non-negative offsets before converting the offset to an spi. All valid stack objects begin at a negative offset from the frame pointer.",
    "evidence": "osv:CVE-2026-98599",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98599",
      "aliases": [
        "CVE-2026-98599"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "06accc8779c1d558a5b5a21f2ac82b0c95827ddd"
                },
                {
                  "fixed": "89a7241fc7ecc1b5e47c3f071081e314523b8d9d"
                },
                {
                  "fixed": "79a9172f3ab4ad8392c5e5c8944b9b7710ade620"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98599.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.4.0"
                },
                {
                  "fixed": "7.2.9"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98599.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.982174373Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/79a9172f3ab4ad8392c5e5c8944b9b7710ade620",
        "https://git.kernel.org/stable/c/89a7241fc7ecc1b5e47c3f071081e314523b8d9d",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98599.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98599",
        "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-2026-98599.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98599",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 491648,
  "published_at": "2026-10-18T15:19:11.941+00:00"
}