CVE-2026-64269 (GCVE-0-2026-64269)
Vulnerability from cvelistv5
Published
2026-07-25 08:49
Modified
2026-08-23 12:45
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg When the server answers an RTRS READ, rdma_write_sg() builds the source scatter/gather entry for the IB_WR_RDMA_WRITE that returns data to the peer. Its length is taken directly from the wire descriptor: plist->length = le32_to_cpu(id->rd_msg->desc[0].len); rd_msg points into the chunk buffer that the remote peer filled via RDMA-WRITE-WITH-IMM (rtrs_srv_rdma_done() -> process_io_req() -> process_read()), so desc[0].len is attacker-controlled and, before this change, was only rejected when zero. The source address is the fixed chunk start (dma_addr[msg_id]) and the source lkey is the PD-wide local_dma_lkey, which is not tied to the chunk's MR mapping, so the verbs layer does not constrain the transfer length to max_chunk_size. msg_id and off are bounded against queue_depth and max_chunk_size in rtrs_srv_rdma_done(), but desc[0].len is a separate field that was not checked against the chunk size. A peer that advertises desc[0].len larger than max_chunk_size can make the posted RDMA write read past the chunk's mapped region. The resulting behaviour depends on the IOMMU configuration: with no IOMMU or in passthrough mode the read may extend into memory adjacent to the chunk and be returned to the peer, which can disclose host memory; with a translating IOMMU the out-of-range access is expected to fault and abort the connection. In either case the transfer exceeds what the protocol permits and is driven by a remote peer. Reject a descriptor length above max_chunk_size, mirroring the existing off >= max_chunk_size bound in rtrs_srv_rdma_done(). Legitimate clients do not exceed it: the client sets desc[0].len to its MR length, which is capped at the negotiated max_io_size (max_chunk_size - MAX_HDR_SIZE).
References
Impacted products
Vendor Product Version
Linux Linux Version: 9cb837480424e78ed585376f944088246685aec3
Version: 9cb837480424e78ed585376f944088246685aec3
Version: 9cb837480424e78ed585376f944088246685aec3
Version: 9cb837480424e78ed585376f944088246685aec3
Version: 9cb837480424e78ed585376f944088246685aec3
Version: 9cb837480424e78ed585376f944088246685aec3
Version: 9cb837480424e78ed585376f944088246685aec3
Version: 9cb837480424e78ed585376f944088246685aec3
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/ulp/rtrs/rtrs-srv.c"
          ],
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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            }
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg\n\nWhen the server answers an RTRS READ, rdma_write_sg() builds the source\nscatter/gather entry for the IB_WR_RDMA_WRITE that returns data to the\npeer. Its length is taken directly from the wire descriptor:\n\n  plist-\u003elength = le32_to_cpu(id-\u003erd_msg-\u003edesc[0].len);\n\nrd_msg points into the chunk buffer that the remote peer filled via\nRDMA-WRITE-WITH-IMM (rtrs_srv_rdma_done() -\u003e process_io_req() -\u003e\nprocess_read()), so desc[0].len is attacker-controlled and, before this\nchange, was only rejected when zero. The source address is the fixed\nchunk start (dma_addr[msg_id]) and the source lkey is the PD-wide\nlocal_dma_lkey, which is not tied to the chunk\u0027s MR mapping, so the verbs\nlayer does not constrain the transfer length to max_chunk_size. msg_id\nand off are bounded against queue_depth and max_chunk_size in\nrtrs_srv_rdma_done(), but desc[0].len is a separate field that was not\nchecked against the chunk size.\n\nA peer that advertises desc[0].len larger than max_chunk_size can make\nthe posted RDMA write read past the chunk\u0027s mapped region. The resulting\nbehaviour depends on the IOMMU configuration: with no IOMMU or in\npassthrough mode the read may extend into memory adjacent to the chunk\nand be returned to the peer, which can disclose host memory; with a\ntranslating IOMMU the out-of-range access is expected to fault and abort\nthe connection. In either case the transfer exceeds what the protocol\npermits and is driven by a remote peer.\n\nReject a descriptor length above max_chunk_size, mirroring the existing\noff \u003e= max_chunk_size bound in rtrs_srv_rdma_done(). Legitimate clients\ndo not exceed it: the client sets desc[0].len to its MR length, which is\ncapped at the negotiated max_io_size (max_chunk_size - MAX_HDR_SIZE)."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - RTRS accepts network connections over routable RDMA transports including RoCE and iWARP, and the malicious descriptor is supplied by a remote peer.\nAC:L - The peer directly controls the descriptor length and destination buffer; no race, timing, or victim-controlled state is required in no-IOMMU, passthrough, or software-RDMA deployments.\nPR:N - The handshake validates protocol fields but performs no credential, capability, or authentication check before publishing chunk rkeys and accepting I/O requests.\nUI:N - After connecting, the attacker can submit the crafted RDMA READ request without any victim action.\nS:U - The vulnerable RTRS module and affected host memory remain within the kernel\u0027s security authority; a translating IOMMU prevents rather than permits crossing its isolation boundary.\nC:H - The PD-wide local DMA key does not constrain the attacker-supplied transfer length, permitting a broad out-of-bounds read of adjacent host memory that is returned to the peer.\nI:N - The malformed operation reads server memory and writes it only to the peer\u0027s registered destination; it provides no server-side memory-write primitive.\nA:H - Software-RDMA can CPU-copy through invalid pages and oops or crash, while hardware or IOMMU faults can abort paths. An unauthenticated peer can trigger the condition repeatedly."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-23T12:45:35.835Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a35b7a8728a53ddc80b323970689fa5985816836"
        },
        {
          "url": "https://git.kernel.org/stable/c/68c09762172f6224e9ddf9b0a60bacbb36e443eb"
        },
        {
          "url": "https://git.kernel.org/stable/c/6cada540150894e81042a0ae0c796a21a9a877da"
        },
        {
          "url": "https://git.kernel.org/stable/c/2912f3d40355dabc08fdbaaf2764d02445fe88dc"
        },
        {
          "url": "https://git.kernel.org/stable/c/6f40246f4312fdbab5a13cc440adebf95eb2aa66"
        },
        {
          "url": "https://git.kernel.org/stable/c/5a45d0aa1fa50a333ce5763ade744e2d89838667"
        },
        {
          "url": "https://git.kernel.org/stable/c/da3e44add94b05dfde56f898421922f5cf35705f"
        },
        {
          "url": "https://git.kernel.org/stable/c/963af8d97a8c6a117134a8d0db1415e0489200b1"
        }
      ],
      "title": "RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64269",
    "datePublished": "2026-07-25T08:49:16.946Z",
    "dateReserved": "2026-07-19T15:36:31.775Z",
    "dateUpdated": "2026-08-23T12:45:35.835Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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