net: ip_tunnel: initialize `options_len` before referencing options

{
  "id": "8d8148ed49a47a8ccc4e40084a20a02e8e2166cf4e6cebd456d2380fa6e3ede1",
  "url": "https://osv.dev/vulnerability/CVE-2026-98240",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: ip_tunnel: initialize `options_len` before referencing options",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net: ip_tunnel: initialize `options_len` before referencing options The following command triggers a kernel panic: ip link add d0 type dummy; ip link set d0 up ip route add 10.30.0.0/16 \\ encap ip id 300 geneve_opts 4660:66:11223344 dev d0 memcpy: detected buffer overflow: 4 byte write of buffer size 0 kernel BUG at lib/string_helpers.c:1044! ... ip_tun_parse_opts.part.0.cold+0x10/0x10 ip_tun_build_state+0x116/0x2a0 On kernels built with GCC 15+ and `CONFIG_FORTIFY_SOURCE`, the fortified `memcpy()` got 0 sized destination with request of 4 bytes length: static int ip_tun_parse_opts_geneve(...) { ... attr = tb[LWTUNNEL_IP_OPT_GENEVE_DATA]; data_len = nla_len(attr); /* == 4 */ struct geneve_opt *opt = ip_tunnel_info_opts(info) + opts_len; memcpy(opt->opt_data, nla_data(attr), data_len); /* ^^^^^^^^^^^^^ 0 since options_len is assigned afterwards */ Fixed by initializing the counter before the options are referenced. Matching what `tunnel_key_opts_set()` already does.",
    "evidence": "osv:CVE-2026-98240",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.54",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98240",
      "aliases": [
        "CVE-2026-98240"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "bb5e62f2d547c4de6d1b144cbce2373a76c33f18"
                },
                {
                  "fixed": "9907325257b4b382f26aafd5d9a8d47915907dd5"
                },
                {
                  "fixed": "0f6a6beb01c068fcd5274eabf22c260039749fea"
                },
                {
                  "fixed": "455ebeadf714f51e1dbbd6a022c74c9215b1cd76"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98240.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.15.0"
                },
                {
                  "fixed": "6.18.54"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98240.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:35.817489299Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0f6a6beb01c068fcd5274eabf22c260039749fea",
        "https://git.kernel.org/stable/c/455ebeadf714f51e1dbbd6a022c74c9215b1cd76",
        "https://git.kernel.org/stable/c/9907325257b4b382f26aafd5d9a8d47915907dd5",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98240.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98240",
        "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-2026-98240.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98240",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 503410,
  "published_at": "2026-10-06T08:45:11.284+00:00"
}