CVE-2025-40169 (GCVE-0-2025-40169)
Vulnerability from cvelistv5
Published
2025-11-12 10:46
Modified
2025-11-12 10:46
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject negative offsets for ALU ops When verifying BPF programs, the check_alu_op() function validates instructions with ALU operations. The 'offset' field in these instructions is a signed 16-bit integer. The existing check 'insn->off > 1' was intended to ensure the offset is either 0, or 1 for BPF_MOD/BPF_DIV. However, because 'insn->off' is signed, this check incorrectly accepts all negative values (e.g., -1). This commit tightens the validation by changing the condition to '(insn->off != 0 && insn->off != 1)'. This ensures that any value other than the explicitly permitted 0 and 1 is rejected, hardening the verifier against malformed BPF programs.
References
Impacted products
Vendor Product Version
Linux Linux Version: ec0e2da95f72d4a46050a4d994e4fe471474fd80
Version: ec0e2da95f72d4a46050a4d994e4fe471474fd80
Version: ec0e2da95f72d4a46050a4d994e4fe471474fd80
Version: ec0e2da95f72d4a46050a4d994e4fe471474fd80
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{
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          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
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              "version": "0",
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject negative offsets for ALU ops\n\nWhen verifying BPF programs, the check_alu_op() function validates\ninstructions with ALU operations. The \u0027offset\u0027 field in these\ninstructions is a signed 16-bit integer.\n\nThe existing check \u0027insn-\u003eoff \u003e 1\u0027 was intended to ensure the offset is\neither 0, or 1 for BPF_MOD/BPF_DIV. However, because \u0027insn-\u003eoff\u0027 is\nsigned, this check incorrectly accepts all negative values (e.g., -1).\n\nThis commit tightens the validation by changing the condition to\n\u0027(insn-\u003eoff != 0 \u0026\u0026 insn-\u003eoff != 1)\u0027. This ensures that any value\nother than the explicitly permitted 0 and 1 is rejected, hardening the\nverifier against malformed BPF programs."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-11-12T10:46:51.736Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/3bce44b344040e5eef3d64d38b157c15304c0aab"
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        },
        {
          "url": "https://git.kernel.org/stable/c/21167bf70dbe400563e189ac632258d35eda38b5"
        },
        {
          "url": "https://git.kernel.org/stable/c/55c0ced59fe17dee34e9dfd5f7be63cbab207758"
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      ],
      "title": "bpf: Reject negative offsets for ALU ops",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40169",
    "datePublished": "2025-11-12T10:46:51.736Z",
    "dateReserved": "2025-04-16T07:20:57.176Z",
    "dateUpdated": "2025-11-12T10:46:51.736Z",
    "state": "PUBLISHED"
  },
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  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40169\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-11-12T11:15:47.270\",\"lastModified\":\"2025-11-12T16:19:12.850\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbpf: Reject negative offsets for ALU ops\\n\\nWhen verifying BPF programs, the check_alu_op() function validates\\ninstructions with ALU operations. The \u0027offset\u0027 field in these\\ninstructions is a signed 16-bit integer.\\n\\nThe existing check \u0027insn-\u003eoff \u003e 1\u0027 was intended to ensure the offset is\\neither 0, or 1 for BPF_MOD/BPF_DIV. However, because \u0027insn-\u003eoff\u0027 is\\nsigned, this check incorrectly accepts all negative values (e.g., -1).\\n\\nThis commit tightens the validation by changing the condition to\\n\u0027(insn-\u003eoff != 0 \u0026\u0026 insn-\u003eoff != 1)\u0027. This ensures that any value\\nother than the explicitly permitted 0 and 1 is rejected, hardening the\\nverifier against malformed BPF programs.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/21167bf70dbe400563e189ac632258d35eda38b5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3bce44b344040e5eef3d64d38b157c15304c0aab\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5017c302ca4b2a45149ad64e058fa2d5623c068f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/55c0ced59fe17dee34e9dfd5f7be63cbab207758\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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