bpf, arm64: Fix off-by-one in check_imm signed range check_CVE-2026-53036

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, arm64: Fix off-by-one in check_imm signed range check\n\ncheck_imm(bits, imm) is used in the arm64 BPF JIT to verify that\na branch displacement (in arm64 instruction units) fits into the\nsigned N-bit immediate field of a B, B.cond or CBZ/CBNZ encoding\nbefore it is handed to the encoder. The macro currently tests for\n(imm > 0 && imm >> bits) || (imm < 0 && ~imm >> bits) which admits\nvalues in [-2^N, 2^N) \u2014 effectively a signed (N+1)-bit range. A\nsigned N-bit field only holds [-2^(N-1), 2^(N-1)), so the check\nadmits one extra bit of range on each side.\n\nIn particular, for check_imm19(), values in [2^18, 2^19) slip past\nthe check but do not fit into the 19-bit signed imm19 field of\nB.cond. aarch64_insn_encode_immediate() then masks the raw value\ninto the 19-bit field, setting bit 18 (the sign bit) and flipping\na forward branch into a backward one. Same class of issue exists\nfor check_imm26() and the B/BL encoding. Shift by (bits - 1)\ninstead of bits so the actual signed N-bit range is enforced.",
    "published": "2026-06-24T16:29:43.449Z",
    "modified": "2026-06-28T06:38:20.137Z",
    "type": "cve",
    "title": "bpf, arm64: Fix off-by-one in check_imm signed range check",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/a5dfeb3b61065039488342d43ae06d4729d955d4\nhttps://git.kernel.org/stable/c/7fd3b41260c6120e7b60164afea5d961af6224f9\nhttps://git.kernel.org/stable/c/6927f0d6794aa73318bbfa929f1ff6065b0620df\nhttps://git.kernel.org/stable/c/1a113b5497297871699cd498b1b83542e0db7f15\nhttps://git.kernel.org/stable/c/fb74defa1cca1a73177c0c761e641332e4f979a3\nhttps://git.kernel.org/stable/c/1dd8be4ec722ce54e4cace59f3a4ba658111b3ec",
    "id": "CVE-2026-53036",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux e54bcde3d69d40023ae77727213d14f920eb264a\nLinux Linux e54bcde3d69d40023ae77727213d14f920eb264a\nLinux Linux e54bcde3d69d40023ae77727213d14f920eb264a\nLinux Linux e54bcde3d69d40023ae77727213d14f920eb264a\nLinux Linux e54bcde3d69d40023ae77727213d14f920eb264a\nLinux Linux e54bcde3d69d40023ae77727213d14f920eb264a\nLinux Linux 3.18",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "e54bcde3d69d40023ae77727213d14f920eb264a",
    "vendor": "Linux",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}