{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-40139",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2025-40139"
  ],
  "published": "2025-11-12T10:24:04Z",
  "summary": "smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().\n\nsmc_clc_prfx_set() is called during connect() and not under RCU\nnor RTNL.\n\nUsing sk_dst_get(sk)->dev could trigger UAF.\n\nLet's use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()\nafter kernel_getsockname().\n\nNote that the returned value of smc_clc_prfx_set() is not used\nin the caller.\n\nWhile at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()\nnot to touch dst there.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/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": "6.1.187",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-40139"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/80d1fd39f4e37d836655e9f7ffccaf78925049bf"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/956c57daba55cf9ed25d9f2512883b8a1a927599"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0736993bfe5c7a9c744ae3fac62d769dfdae54e1"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/935d783e5de9b64587f3adb25641dd8385e64ddb"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-02T13:01:47Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - `smc_clc_prfx_set()` is only reached from the client side of the CLC handshake, via `connect()` on a locally created AF_SMC socket (`smc_connect` \u2192 `__smc_connect` \u2192 `smc_clc_send_proposal`). The attacker must have local code execution to initiate the connection, so the vector is Local even though the leaked bytes are subsequently sent to a remote peer.\nAC:L - The attacker drives both sides of the race \u2014 one thread loops `connect()` on AF_SMC sockets (the stale `dst->dev` dereference), while another repeatedly creates and deletes net_devices to force `dst_dev_put()`/`free_netdev()`, which unprivileged users can do freely inside a user namespace with CAP_NET_ADMIN. No condition depends on state outside the attacker's influence, and the window is widened at will by using non-blocking connect so the work runs in `smc_connect_work`.\nPR:L - `smc_create()` performs no capability check and `MODULE_ALIAS_NETPROTO(PF_SMC)` lets any unprivileged user autoload the module; the netdev teardown side needs CAP_NET_ADMIN, which is obtainable by an ordinary user via `unshare -Urn` and therefore counts as Low, not High.\nUI:N - The attacker's own process performs every step \u2014 creating the SMC socket, connecting to a listener it controls, and tearing down the device \u2014 with no action required from any other user or administrator.\nS:U - The use-after-free touches the freed `net_device` slab and the `in_device`/`inet6_dev` structures it points to, all within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed `net_device` is dereferenced and its `ifa_list`/`addr_list` walked, and a reclaimed slab can be groomed with attacker-controlled data, yielding an arbitrary kernel-memory read; worse, `smc_clc_prfx_set6_rcu()` copies up to 8 prefixes out of that freed memory into the CLC Proposal that `smc_clc_send_proposal()` transmits, exfiltrating freed kernel bytes onto the wire.\nI:H - A use-after-free on a `net_device` is a heap-corruption primitive \u2014 the reclaimed object's contents are attacker-influenceable through heap spraying and the code follows pointers out of it (`dev->ip_ptr`, `dev->ip6_ptr`, list heads), which can be groomed into an arbitrary write and control-flow hijack.\nA:H - Dereferencing the freed device and walking a bogus `in_dev`/`inet6_dev` address list reliably produces a kernel oops or panic, or an unbounded list walk that hangs the CPU, and the attacker can repeat the attempt indefinitely."
    }
  }
}