{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-72466",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-72466"
  ],
  "published": "2026-08-15T06:04:33Z",
  "summary": "xprtrdma: Fix bcall rep leak and unbounded peek",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nxprtrdma: Fix bcall rep leak and unbounded peek\n\nrpcrdma_is_bcall() decodes a reply's first words to decide whether\nthe frame is a backchannel call. Two issues in that decode path\nlet a short or malformed reply leak the receive buffer and drain\nthe Receive queue.\n\nFirst, the speculative peek\n\n    p = xdr_inline_decode(xdr, 0);\n    /* five p++ reads follow */\n\nasks xdr_inline_decode() for zero bytes, which returns xdr->p\nwithout consulting xdr->end. The five subsequent __be32 reads can\nthen walk up to 20 bytes past the wire payload into stale regbuf\ncontents and misclassify the reply as a backchannel call.\n\nSecond, after the post-peek\n\n    p = xdr_inline_decode(xdr, 3 * sizeof(*p));\n    if (unlikely(!p))\n            return true;\n\nthe short-header arm returns true without calling\nrpcrdma_bc_receive_call(). The contract with the caller is that a\ntrue return transfers ownership of rep to the backchannel path:\n\n    rpcrdma_reply_handler()\n      if (rpcrdma_is_bcall(r_xprt, rep))\n              return;        /* bare return, skips out_post */\n      ...\n    out_post:\n      rpcrdma_post_recvs(r_xprt, credits + ...);\n\nBecause rpcrdma_bc_receive_call() never ran, no one took rep, but\nrpcrdma_reply_handler still bare-returns past rpcrdma_rep_put()\nand rpcrdma_post_recvs(). The rep, with its persistently\nDMA-mapped receive buffer, is orphaned on rb_all_reps and freed\nonly at transport teardown. This completion reposts nothing, so\nits slot is reclaimed only when a later forward-channel reply\nreaches out_post and rpcrdma_post_recvs() allocates a fresh rep to\nbackfill; absent that traffic the Receive queue drains and the\npeer's Sends draw RNR NAKs.\n\nFix by consulting xdr->end after the zero-length peek so the five\n__be32 reads cannot run unless 20 bytes of wire payload remain. A\nbyte-precise comparison against xdr->end is required because a\nnon-4-aligned receive rounds the stream's word count up past the\ntrue payload. Also return false from the short-header arm so the\nreply falls through the normal out_norqst cleanup chain\n(rpcrdma_rep_put() plus rpcrdma_post_recvs()).",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.178",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-72466"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0cee8f9c3b14bd6dee9c4310090a7f45b89b834f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7afc2f8d2fd9394724df9eaf22ce7a71029a5fba"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/88b5346284a184a6b7d019912232a571d672d3e3"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/07aa506436be7634e381e1e1f6d0efa9efc81ecc"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d7a2870dde3bb09d51d6b9c877642996ad6b92dd"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/118a16a18c59f7ad8084b2d13988839b669fca10"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c7653d5cebc8492c77ec0415b5e9c0fb3e644bc6"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-17T05:50:24Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - The bug is reached when a remote RDMA peer's inbound message completes in rpcrdma_wc_receive() and rpcrdma_reply_handler() decodes it; a malicious or compromised NFS-over-RDMA server can send crafted short rdma_msg replies over the established RPC/RDMA connection without local access.\nAC:L - On an active NFSv4.1+ RPC/RDMA session the attacker fully controls inbound replies and can repeatedly send short/malformed rdma_msg frames to hit the zero-length peek and short-header return-true paths, reliably leaking receive buffers and draining the Receive queue.\nPR:N - Exploitation requires only network reachability as the connected RDMA/RPC peer (e.g., a malicious NFS server); no local account, mount privileges, or namespaced capabilities on the victim NFS client are needed to deliver the malformed RDMA replies.\nUI:N - Once an NFS-over-RDMA mount and NFSv4.1 backchannel session exist, triggering the flaw needs no additional victim action beyond the attacker sending malicious RDMA receive payloads during normal client-server communication.\nS:U - The vulnerability and its impact remain within the NFS client's kernel SUNRPC/xprtrdma transport context; it does not cross a VM, container, or IOMMU security boundary to affect other authorities.\nC:H - xdr_inline_decode(xdr,0) permits up to five subsequent __be32 reads past the wire payload into stale receive-buffer contents, an out-of-bounds read that can misclassify replies and expose remnants of prior RPC/NFS data to unintended processing paths.\nI:H - Stale-buffer-assisted misclassification can treat a forward-channel reply as a backchannel RPC_CALL, a type confusion that routes attacker-influenced bytes into rpcrdma_bc_receive_call()/NFSv4 callback handling and can corrupt client session state.\nA:H - Each successful trigger orphans a DMA-mapped rpcrdma_rep and skips rpcrdma_post_recvs(), monotonically draining the RDMA Receive queue until the peer gets RNR NAKs and the NFS-over-RDMA connection becomes unusable, enabling sustained remote denial of service."
    }
  }
}