fkie_cve-2025-40169
Vulnerability from fkie_nvd
Published
2025-11-12 11:15
Modified
2025-11-12 16:19
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
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/21167bf70dbe400563e189ac632258d35eda38b5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3bce44b344040e5eef3d64d38b157c15304c0aab
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5017c302ca4b2a45149ad64e058fa2d5623c068f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/55c0ced59fe17dee34e9dfd5f7be63cbab207758
Impacted products
Vendor Product Version


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{
  "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."
    }
  ],
  "id": "CVE-2025-40169",
  "lastModified": "2025-11-12T16:19:12.850",
  "metrics": {},
  "published": "2025-11-12T11:15:47.270",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "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"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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