CVE-2026-31667: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mxvq-qhx2-fp47",
  "modified" : "2026-04-27T15:30:46Z",
  "published" : "2026-04-24T15:32:37Z",
  "aliases" : [ "CVE-2026-31667" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nInput: uinput - fix circular locking dependency with ff-core\n\nA lockdep circular locking dependency warning can be triggered\nreproducibly when using a force-feedback gamepad with uinput (for\nexample, playing ELDEN RING under Wine with a Flydigi Vader 5\ncontroller):\n\n  ff->mutex -> udev->mutex -> input_mutex -> dev->mutex -> ff->mutex\n\nThe cycle is caused by four lock acquisition paths:\n\n1. ff upload: input_ff_upload() holds ff->mutex and calls\n   uinput_dev_upload_effect() -> uinput_request_submit() ->\n   uinput_request_send(), which acquires udev->mutex.\n\n2. device create: uinput_ioctl_handler() holds udev->mutex and calls\n   uinput_create_device() -> input_register_device(), which acquires\n   input_mutex.\n\n3. device register: input_register_device() holds input_mutex and\n   calls kbd_connect() -> input_register_handle(), which acquires\n   dev->mutex.\n\n4. evdev release: evdev_release() calls input_flush_device() under\n   dev->mutex, which calls input_ff_flush() acquiring ff->mutex.\n\nFix this by introducing a new state_lock spinlock to protect\nudev->state and udev->dev access in uinput_request_send() instead of\nacquiring udev->mutex.  The function only needs to atomically check\ndevice state and queue an input event into the ring buffer via\nuinput_dev_event() -- both operations are safe under a spinlock\n(ktime_get_ts64() and wake_up_interruptible() do not sleep).  This\nbreaks the ff->mutex -> udev->mutex link since a spinlock is a leaf in\nthe lock ordering and cannot form cycles with mutexes.\n\nTo keep state transitions visible to uinput_request_send(), protect\nwrites to udev->state in uinput_create_device() and\nuinput_destroy_device() with the same state_lock spinlock.\n\nAdditionally, move init_completion(&request->done) from\nuinput_request_send() to uinput_request_submit() before\nuinput_request_reserve_slot().  Once the slot is allocated,\nuinput_flush_requests() may call complete() on it at any time from\nthe destroy path, so the completion must be initialised before the\nrequest becomes visible.\n\nLock ordering after the fix:\n\n  ff->mutex -> state_lock (spinlock, leaf)\n  udev->mutex -> state_lock (spinlock, leaf)\n  udev->mutex -> input_mutex -> dev->mutex -> ff->mutex (no back-edge)",
  "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" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-31667"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/1534661043c434b81cfde26b97a2fb2460329cf0"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/1e09dfbb4f5d20ee111f92325a00f85778a5f328"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/271ee71a1917b89f6d73ec82dd091c33d92ee617"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/4cda78d6f8bf2b700529f2fbccb994c3e826d7c2"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/546c18a14924eb521fe168d916d7ce28f1e13c1d"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/71a9729f412e2c692a35c542e14b706fb342927f"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/974f7b138c3a96dd5cd53d1b33409cd7b2229dc6"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/a3d6c9c053c9c605651508569230ead633b13f76"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-362", "CWE-667" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-04-24T15:16:46Z"
  }
}