riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args

{
  "id": "64f9b13b70c7f45e8f1fcb075e23638e05ac1f9be54d5cdad181d7c29c70670a",
  "url": "https://osv.dev/vulnerability/CVE-2026-90195",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args On RV64, the ABI requires sign-extension for signed 1-byte and 2-byte kfunc args. However, the RV64 JIT currently does not perform sign-extension for such kfunc args. Before commit 7ce090afbf72 (\"bpf: Infer zext_dst based on static register liveness analysis\"), state pruning could potentially omit zero-extension of 32-bit subregisters, which inadvertently masked the above issue by making the args appear as if they had been properly sign-extended. After that commit, the problem is exposed, causing the kfunc_call/kfunc_call_test4 selftest to fail. Fix this by extending the existing sign-extension logic to handle signed 1-byte and 2-byte kfunc args as well.",
    "evidence": "osv:CVE-2026-90195",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.110",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.52",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-90195",
      "aliases": [
        "CVE-2026-90195"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "555fc6f1caf00ce7005e732b688da26c0dc3c5c5"
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                {
                  "fixed": "801ae90f8ce099187e6224cec7d72d07a4df0324"
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                {
                  "fixed": "71dbd143be598954ae103feadd12692aeb0f2f88"
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                {
                  "fixed": "f2aaa621591093cfe8224a25ef2f04a3b1e304b0"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90195.json"
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        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.9.0"
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                {
                  "fixed": "6.12.110"
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.13.0"
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                {
                  "fixed": "6.18.52"
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              ]
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
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                {
                  "fixed": "7.2.6"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90195.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.024194792Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/555fc6f1caf00ce7005e732b688da26c0dc3c5c5",
        "https://git.kernel.org/stable/c/71dbd143be598954ae103feadd12692aeb0f2f88",
        "https://git.kernel.org/stable/c/801ae90f8ce099187e6224cec7d72d07a4df0324",
        "https://git.kernel.org/stable/c/f2aaa621591093cfe8224a25ef2f04a3b1e304b0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90195.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-90195",
        "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-2026-90195.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-90195",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 504446,
  "published_at": "2026-09-17T16:07:14.979+00:00"
}