RDMA/rxe: Reject unknown opcodes before ICRC processing_CVE-2026-46133

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: Reject unknown opcodes before ICRC processing\n\nEven after applying commit 7244491dab34 (\"RDMA/rxe: Validate pad and ICRC\nbefore payload_size() in rxe_rcv\"), a single unauthenticated UDP packet\ncan still trigger panic.  That patch handled payload_size() underflow only\nfor valid opcodes with short packets, not for packets carrying an unknown\nopcode.  The unknown-opcode OOB read described below predates that commit\nand reaches back to the initial Soft RoCE driver.\n\nThe check added there reads\n\n    pkt->paylen < header_size(pkt) + bth_pad(pkt) + RXE_ICRC_SIZE\n\nwhere header_size(pkt) expands to rxe_opcode[pkt->opcode].length.  The\nrxe_opcode[] array has 256 entries but is only populated for defined IB\nopcodes; any other entry (for example opcode 0xff) is zero-initialized, so\nlength == 0 and the check degenerates to\n\n    pkt->paylen < 0 + bth_pad(pkt) + RXE_ICRC_SIZE\n\nwhich does not constrain pkt->paylen enough.  rxe_icrc_hdr() then computes\n\n    rxe_opcode[pkt->opcode].length - RXE_BTH_BYTES\n\nwhich underflows when length == 0 and passes a huge value to rxe_crc32(),\ncausing an out-of-bounds read of the skb payload.\n\nReproduced on v7.0-rc7 with that fix applied, QEMU/KVM with\nCONFIG_RDMA_RXE=y and CONFIG_KASAN=y, after\n\n    rdma link add rxe0 type rxe netdev eth0\n\nA single 48-byte UDP packet to port 4791 with BTH opcode=0xff and\nQPN=IB_MULTICAST_QPN triggers:\n\n    BUG: KASAN: slab-out-of-bounds in crc32_le+0x115/0x170\n    Read of size 1 at addr ...\n    The buggy address is located 0 bytes to the right of\n     allocated 704-byte region\n    Call Trace:\n     crc32_le+0x115/0x170\n     rxe_icrc_hdr.isra.0+0x226/0x300\n     rxe_icrc_check+0x13f/0x3a0\n     rxe_rcv+0x6e1/0x16e0\n     rxe_udp_encap_recv+0x20a/0x320\n     udp_queue_rcv_one_skb+0x7ed/0x12c0\n\nSubsequent packets with the same shape fault on unmapped memory and panic\nthe kernel.  The trigger requires only module load and \"rdma link add\"; no\nQP, no connection, and no authentication.\n\nFix this by rejecting packets whose opcode has no rxe_opcode[] entry,\ndetected via the zero mask or zero length, before any length arithmetic\nruns.",
    "published": "2026-05-28T09:35:47.819Z",
    "modified": "2026-05-30T10:48:09.919Z",
    "type": "cve",
    "title": "RDMA/rxe: Reject unknown opcodes before ICRC processing",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/e3dc3a2fb05f4ed49c7f20594c4c52350d032189\nhttps://git.kernel.org/stable/c/f8ee926431a7bbec2b10c1290664af2cb290b983\nhttps://git.kernel.org/stable/c/006a3a5f75345c6a0dbf13fd3ee01406e93b6733\nhttps://git.kernel.org/stable/c/6fa18025e5782afff91415fd5217b39c1e4837d7\nhttps://git.kernel.org/stable/c/4c6f86d85d03cdb33addce86aa69aa795ca6c47a",
    "id": "CVE-2026-46133",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux 8700e3e7c4857d28ebaa824509934556da0b3e76\nLinux Linux 8700e3e7c4857d28ebaa824509934556da0b3e76\nLinux Linux 8700e3e7c4857d28ebaa824509934556da0b3e76\nLinux Linux 8700e3e7c4857d28ebaa824509934556da0b3e76\nLinux Linux 8700e3e7c4857d28ebaa824509934556da0b3e76\nLinux Linux 4.8",
    "sourceHref": "",
    "cvss": {
        "score": 7.5,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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": "",
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            "privilegesRequired": "",
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            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "8700e3e7c4857d28ebaa824509934556da0b3e76",
    "vendor": "Linux",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
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    "ai_score": 0
}