{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-54269",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2023-54269"
  ],
  "published": "2025-12-30T12:20:26Z",
  "summary": "SUNRPC: double free xprt_ctxt while still in use",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: double free xprt_ctxt while still in use\n\nWhen an RPC request is deferred, the rq_xprt_ctxt pointer is moved out\nof the svc_rqst into the svc_deferred_req.\nWhen the deferred request is revisited, the pointer is copied into\nthe new svc_rqst - and also remains in the svc_deferred_req.\n\nIn the (rare?) case that the request is deferred a second time, the old\nsvc_deferred_req is reused - it still has all the correct content.\nHowever in that case the rq_xprt_ctxt pointer is NOT cleared so that\nwhen xpo_release_xprt is called, the ctxt is freed (UDP) or possible\nadded to a free list (RDMA).\nWhen the deferred request is revisited for a second time, it will\nreference this ctxt which may be invalid, and the free the object a\nsecond time which is likely to oops.\n\nSo change svc_defer() to *always* clear rq_xprt_ctxt, and assert that\nthe value is now stored in the svc_deferred_req.",
  "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": [
        "1:6.1.21-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v6",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v8",
            "binary_version": "1:6.1.21-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.21-1+rpt1": {
            "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed",
            "upstream_version": "6.1.21",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.30"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-54269"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7851771789e87108a92697194105ef0c9307dc5e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fd86534872f445f54dc01e7db001e25eadf063a8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e0c648627322a4c7e018e5c7f837c3c03e297dbb"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/eb8d3a2c809abd73ab0a060fe971d6b9019aa3c1"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:24:39Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - The vulnerable path is nfsd/sunrpc server-side request processing driven entirely by RPC datagrams received from remote clients over UDP port 2049 (or NFS/RDMA). No local access is needed; the attacker only sends network packets to the NFS server.\nAC:L - The attacker controls both deferral triggers \u2014 a novel (freely spoofable) UDP source address forces an ip_map cache miss, and an unresolved export/filehandle forces a second nfsd_fh/nfsd_export miss on the same request, which is exactly the first-contact sequence for a new client. Small datagrams stay linear so rq_xprt_ctxt is populated, making the trigger repeatable at will.\nPR:N - The deferrals occur inside svcauth_unix_set_client() and the export lookup, i.e. while the server is still deciding whether the client is permitted at all, so no credentials have been verified. AUTH_NULL/AUTH_UNIX requests from any host able to reach the nfsd port suffice.\nUI:N - nfsd threads process incoming RPCs and requeue deferred requests automatically with no action by any local user or administrator.\nS:U - The corruption is confined to kernel memory managed by the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed sk_buff is re-read and re-released (skb->users, skb->head, skb->destructor) and the double free returns the same slab object to two owners, giving type-confusion-based read primitives over adjacent kernel data. Per UAF guidance this is High.\nI:H - A double free of an sk_buff lets a remote attacker who reallocates the slot with sprayed packet data control fields such as skb->destructor and skb->head, yielding arbitrary write / control-flow hijack; the RDMA variant double-adds a recv ctxt to the free list so two live receives share one DMA buffer.\nA:H - The commit itself notes the second free \"is likely to oops\"; a double free of an sk_buff or corruption of the RDMA recv ctxt free list panics the kernel and can be re-triggered repeatedly by an unauthenticated remote client."
    }
  }
}