GHSA-8QPM-Q6PR-QXF8

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-25 12:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

HID: letsketch: fix UAF on inrange_timer at driver unbind

letsketch_driver does not provide a .remove callback, but letsketch_probe() arms a per-device timer:

timer_setup(&data->inrange_timer, letsketch_inrange_timeout, 0);

The timer is re-armed from letsketch_raw_event() with a 100 ms timeout on every pen-in-range report, and its callback dereferences data->input_tablet to deliver a synthetic BTN_TOOL_PEN release.

letsketch_data is allocated with devm_kzalloc(), and its input_dev fields are devm-allocated via letsketch_setup_input_tablet(). On device unbind (USB unplug or rmmod), the HID core runs its default teardown and devm cleanup frees both letsketch_data and the input devices. Because no .remove callback exists, nothing drains the timer first: if raw_event armed it within ~100 ms of the unbind, the pending timer fires on freed memory. This is a UAF read of data and of data->input_tablet, followed by input_report_key() / input_sync() into the freed input_dev.

The same problem can occur on the probe error path: if hid_hw_start() enabled I/O on an always-poll-quirk device and then failed, raw_event may have armed the timer before devm releases data.

Fix by adding a .remove callback that calls hid_hw_stop() first. hid_hw_stop() synchronously kills the URBs that deliver raw_event(), so once it returns no path can re-arm the timer. timer_shutdown_sync() then drains any in-flight callback and permanently disables further mod_timer() calls. Apply the same timer_shutdown_sync() in the probe error path so the timer is guaranteed not to outlive data.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-64365"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:19Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nHID: letsketch: fix UAF on inrange_timer at driver unbind\n\nletsketch_driver does not provide a .remove callback, but\nletsketch_probe() arms a per-device timer:\n\n    timer_setup(\u0026data-\u003einrange_timer, letsketch_inrange_timeout, 0);\n\nThe timer is re-armed from letsketch_raw_event() with a 100 ms\ntimeout on every pen-in-range report, and its callback dereferences\ndata-\u003einput_tablet to deliver a synthetic BTN_TOOL_PEN release.\n\nletsketch_data is allocated with devm_kzalloc(), and its input_dev\nfields are devm-allocated via letsketch_setup_input_tablet().  On\ndevice unbind (USB unplug or rmmod), the HID core runs its default\nteardown and devm cleanup frees both letsketch_data and the input\ndevices.  Because no .remove callback exists, nothing drains the\ntimer first: if raw_event armed it within ~100 ms of the unbind,\nthe pending timer fires on freed memory.  This is a UAF read of\ndata and of data-\u003einput_tablet, followed by input_report_key() /\ninput_sync() into the freed input_dev.\n\nThe same problem can occur on the probe error path: if\nhid_hw_start() enabled I/O on an always-poll-quirk device and then\nfailed, raw_event may have armed the timer before devm releases\ndata.\n\nFix by adding a .remove callback that calls hid_hw_stop() first.\nhid_hw_stop() synchronously kills the URBs that deliver raw_event(),\nso once it returns no path can re-arm the timer.  timer_shutdown_sync()\nthen drains any in-flight callback and permanently disables further\nmod_timer() calls.  Apply the same timer_shutdown_sync() in the probe\nerror path so the timer is guaranteed not to outlive data.",
  "id": "GHSA-8qpm-q6pr-qxf8",
  "modified": "2026-07-25T12:31:33Z",
  "published": "2026-07-25T12:31:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64365"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/17f5928d7010bc9e002930326b59e60e40c09ee3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2bb6e7143cf70ed281822d26c1848b2897ac36e9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3eca1a8165b5e7996e699e9df76cb4645e184d42"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/46c8beeccd8ab2c863827254a85ea877654a3534"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/523db788c0f84612707638e266e8957ca7e3a756"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/df3d8aa1a9392da3de66398e7a03422463806b21"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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