FKIE_CVE-2026-46213

Vulnerability from fkie_nvd - Published: 2026-05-28 10:16 - Updated: 2026-05-28 13:44
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: HID: appletb-kbd: fix UAF in inactivity-timer cleanup path Commit 38224c472a03 ("HID: appletb-kbd: fix slab use-after-free bug in appletb_kbd_probe") added timer_delete_sync(&kbd->inactivity_timer) to both the probe close_hw error path and appletb_kbd_remove(), but the way it was wired in left the inactivity timer reachable during driver tear-down via two distinct windows. Window A -- put_device() before timer_delete_sync(): put_device(&kbd->backlight_dev->dev); timer_delete_sync(&kbd->inactivity_timer); The inactivity_timer softirq reads kbd->backlight_dev and calls backlight_device_set_brightness() -> mutex_lock(&ops_lock). If a concurrent hid_appletb_bl unbind drops the last devm reference between these two calls, the backlight_device is freed and the mutex_lock() touches freed memory. Window B -- backlight cleanup before hid_hw_stop(): if (kbd->backlight_dev) { timer_delete_sync(...); put_device(...); } hid_hw_close(hdev); hid_hw_stop(hdev); Even after Window A is closed, hid_hw_close()/hid_hw_stop() still run afterwards, so a late ".event" callback from the HID core (USB URB completion on real Apple hardware) can arrive after timer_delete_sync() drained the softirq but before put_device() drops the reference. That callback reaches reset_inactivity_timer(), which calls mod_timer() and re-arms the timer. The freshly re-armed timer can then fire on the about-to-be-freed backlight_device. Both windows produce the same KASAN slab-use-after-free: BUG: KASAN: slab-use-after-free in __mutex_lock+0x1aab/0x21c0 Read of size 8 at addr ffff88803ee9a108 by task swapper/0/0 Call Trace: <IRQ> __mutex_lock backlight_device_set_brightness appletb_inactivity_timer call_timer_fn run_timer_softirq handle_softirqs Allocated by task N: devm_backlight_device_register appletb_bl_probe Freed by task M: (concurrent hid_appletb_bl unbind path) Close both windows at once by reworking the tear-down in appletb_kbd_remove() and in the probe close_hw error path so that 1) hid_hw_close()/hid_hw_stop() run before the backlight cleanup, guaranteeing no further .event callback can fire and re-arm the timer, and 2) inside the "if (kbd->backlight_dev)" block, timer_delete_sync() runs before put_device(), so the softirq is drained before the final reference is dropped.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4db2af929279c799b5653a39eb0795c72baffca4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/59a79938ca5541fe55d675304116b7ea684afef0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/93d989e47bc316c793a69c6a332e053c90e29f02
Impacted products
Vendor Product Version
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nHID: appletb-kbd: fix UAF in inactivity-timer cleanup path\n\nCommit 38224c472a03 (\"HID: appletb-kbd: fix slab use-after-free bug in\nappletb_kbd_probe\") added timer_delete_sync(\u0026kbd-\u003einactivity_timer) to\nboth the probe close_hw error path and appletb_kbd_remove(), but the\nway it was wired in left the inactivity timer reachable during driver\ntear-down via two distinct windows.\n\nWindow A -- put_device() before timer_delete_sync():\n\n\tput_device(\u0026kbd-\u003ebacklight_dev-\u003edev);\n\ttimer_delete_sync(\u0026kbd-\u003einactivity_timer);\n\nThe inactivity_timer softirq reads kbd-\u003ebacklight_dev and calls\nbacklight_device_set_brightness() -\u003e mutex_lock(\u0026ops_lock).  If a\nconcurrent hid_appletb_bl unbind drops the last devm reference\nbetween these two calls, the backlight_device is freed and the\nmutex_lock() touches freed memory.\n\nWindow B -- backlight cleanup before hid_hw_stop():\n\n\tif (kbd-\u003ebacklight_dev) {\n\t\ttimer_delete_sync(...);\n\t\tput_device(...);\n\t}\n\thid_hw_close(hdev);\n\thid_hw_stop(hdev);\n\nEven after Window A is closed, hid_hw_close()/hid_hw_stop() still run\nafterwards, so a late \".event\" callback from the HID core (USB URB\ncompletion on real Apple hardware) can arrive after\ntimer_delete_sync() drained the softirq but before put_device() drops\nthe reference.  That callback reaches reset_inactivity_timer(), which\ncalls mod_timer() and re-arms the timer.  The freshly re-armed timer\ncan then fire on the about-to-be-freed backlight_device.\n\nBoth windows produce the same KASAN slab-use-after-free:\n\n  BUG: KASAN: slab-use-after-free in __mutex_lock+0x1aab/0x21c0\n  Read of size 8 at addr ffff88803ee9a108 by task swapper/0/0\n  Call Trace:\n   \u003cIRQ\u003e\n   __mutex_lock\n   backlight_device_set_brightness\n   appletb_inactivity_timer\n   call_timer_fn\n   run_timer_softirq\n   handle_softirqs\n  Allocated by task N:\n   devm_backlight_device_register\n   appletb_bl_probe\n  Freed by task M:\n   (concurrent hid_appletb_bl unbind path)\n\nClose both windows at once by reworking the tear-down in\nappletb_kbd_remove() and in the probe close_hw error path so that\n\n 1) hid_hw_close()/hid_hw_stop() run before the backlight cleanup,\n    guaranteeing no further .event callback can fire and re-arm the\n    timer, and\n 2) inside the \"if (kbd-\u003ebacklight_dev)\" block, timer_delete_sync()\n    runs before put_device(), so the softirq is drained before the\n    final reference is dropped."
    }
  ],
  "id": "CVE-2026-46213",
  "lastModified": "2026-05-28T13:44:01.663",
  "metrics": {},
  "published": "2026-05-28T10:16:36.947",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4db2af929279c799b5653a39eb0795c72baffca4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/59a79938ca5541fe55d675304116b7ea684afef0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/93d989e47bc316c793a69c6a332e053c90e29f02"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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