{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-38717",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2025-38717"
  ],
  "published": "2025-09-04T15:33:55Z",
  "summary": "net: kcm: Fix race condition in kcm_unattach()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: kcm: Fix race condition in kcm_unattach()\n\nsyzbot found a race condition when kcm_unattach(psock)\nand kcm_release(kcm) are executed at the same time.\n\nkcm_unattach() is missing a check of the flag\nkcm->tx_stopped before calling queue_work().\n\nIf the kcm has a reserved psock, kcm_unattach() might get executed\nbetween cancel_work_sync() and unreserve_psock() in kcm_release(),\nrequeuing kcm->tx_work right before kcm gets freed in kcm_done().\n\nRemove kcm->tx_stopped and replace it by the less\nerror-prone disable_work_sync().",
  "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": null,
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-38717"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c0bffbc92a1ca3960fb9cdb8e9f75a68468eb308"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7275dc3bb8f91b23125ff3f47b6529935cf46152"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/798733ee5d5788b12e8a52db1519abc17e826f69"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/52565a935213cd6a8662ddb8efe5b4219343a25d"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T12:19:11Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The race is driven entirely by local syscalls \u2014 creating an AF_KCM socket, `SIOCKCMATTACH`/`SIOCKCMUNATTACH` ioctls, and `close()` \u2014 with no remote packet needed to reach the vulnerable window. No network-facing service parses attacker data on this path.\nAC:L - The attacker controls both sides of the race, running `kcm_release()` in one thread while a second thread issues `SIOCKCMUNATTACH` on the reserved psock, and can retry the loop indefinitely until the window between `cancel_work_sync()` and `unreserve_psock()` is hit. syzbot hit it repeatedly with three separate reproducers, and `CONFIG_AF_KCM` is shipped as a module by major distributions.\nPR:L - There is not a single `capable()` or `CAP_NET_ADMIN` check in `net/kcm/`, and the protocol family autoloads on an unprivileged `socket(AF_KCM, ...)` call via `MODULE_ALIAS_NETPROTO(PF_KCM)`. Any local unprivileged user can attach a TCP socket and trigger the race.\nUI:N - The attacker performs every step \u2014 socket creation, attach, unattach, and close \u2014 from its own threads. No victim action or cooperation is required.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed `struct kcm_sock` is reachable from a workqueue and is reallocatable by the attacker (its own slab cache, refillable simply by creating more KCM sockets), so the UAF yields a read primitive over adjacent/reused kernel objects and can leak arbitrary kernel memory.\nI:H - Queueing work on a freed object makes the workqueue write into freed memory, and `kcm_tx_work()` subsequently operates on attacker-groomed contents, culminating in the indirect call `sk->sk_write_space(sk)` in `kcm_write_msgs()` \u2014 a control-flow hijack / arbitrary-write path, not just corruption.\nA:H - Even unexploited, running `lock_sock()` and `kcm_write_msgs()` on a freed `kcm_sock` produces a KASAN-reported use-after-free, workqueue list corruption, and kernel oops/panic, which any unprivileged user can trigger repeatedly."
    }
  }
}