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CVE-2026-46202

Estado: AnalizadaMedia (5.5)—

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

HID: appletb-kbd: run inactivity autodim from workqueues

The autodim code in hid-appletb-kbd takes backlight_device->ops_lock via backlight_device_set_brightness() -> mutex_lock() from two different atomic contexts:

Both call sites hit the same mutex_lock()-from-atomic bug. Fix them together by moving the blocking work onto the system workqueue:

Cancel both works synchronously during driver tear-down alongside the existing backlight reference drop.

The semantics are unchanged (same delays, same state transitions on dim, turn-off and user activity); only the execution context of the sleeping call changes.

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The timer field and callback are renamed to match their new type; reset_inactivity_timer() keeps its name because it is invoked from input event paths that read naturally as "reset the inactivity timer".

Detalles técnicos trazas, registros y código del informe original
 * appletb_inactivity_timer() is a struct timer_list callback, so it
   runs in softirq context.  Every expiry triggers

     BUG: sleeping function called from invalid context at kernel/locking/mutex.c:591
     Call Trace:
      <IRQ>
      __might_resched
      __mutex_lock
      backlight_device_set_brightness
      appletb_inactivity_timer
      call_timer_fn
      run_timer_softirq

 * reset_inactivity_timer() is called from appletb_kbd_hid_event() and
   appletb_kbd_inp_event().  On real USB hardware these run in
   softirq/IRQ context (URB completion and input-event dispatch).
   When the Touch Bar has already been dimmed or turned off, the
   reset path calls backlight_device_set_brightness() directly to
   restore brightness, producing the same warning.

 * Convert the inactivity timer from struct timer_list to
   struct delayed_work; the callback (appletb_inactivity_work) now
   runs in process context where mutex_lock() is legal.
 * Add a dedicated struct work_struct restore_brightness_work and have
   reset_inactivity_timer() schedule it instead of calling
   backlight_device_set_brightness() directly.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
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  "published": "2026-05-28T10:16:35.860",
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nHID: appletb-kbd: run inactivity autodim from workqueues\n\nThe autodim code in hid-appletb-kbd takes backlight_device->ops_lock\nvia backlight_device_set_brightness() -> mutex_lock() from two\ndifferent atomic contexts:\n\n * appletb_inactivity_timer() is a struct timer_list callback, so it\n   runs in softirq context.  Every expiry triggers\n\n     BUG: sleeping function called from invalid context at kernel/locking/mutex.c:591\n     Call Trace:\n      <IRQ>\n      __might_resched\n      __mutex_lock\n      backlight_device_set_brightness\n      appletb_inactivity_timer\n      call_timer_fn\n      run_timer_softirq\n\n * reset_inactivity_timer() is called from appletb_kbd_hid_event() and\n   appletb_kbd_inp_event().  On real USB hardware these run in\n   softirq/IRQ context (URB completion and input-event dispatch).\n   When the Touch Bar has already been dimmed or turned off, the\n   reset path calls backlight_device_set_brightness() directly to\n   restore brightness, producing the same warning.\n\nBoth call sites hit the same mutex_lock()-from-atomic bug.  Fix them\ntogether by moving the blocking work onto the system workqueue:\n\n * Convert the inactivity timer from struct timer_list to\n   struct delayed_work; the callback (appletb_inactivity_work) now\n   runs in process context where mutex_lock() is legal.\n * Add a dedicated struct work_struct restore_brightness_work and have\n   reset_inactivity_timer() schedule it instead of calling\n   backlight_device_set_brightness() directly.\n\nCancel both works synchronously during driver tear-down alongside the\nexisting backlight reference drop.\n\nThe semantics are unchanged (same delays, same state transitions on\ndim, turn-off and user activity); only the execution context of the\nsleeping call changes.  The timer field and callback are renamed to\nmatch their new type; reset_inactivity_timer() keeps its name because\nit is invoked from input event paths that read naturally as \"reset\nthe inactivity timer\"."
    }
  ],
  "lastModified": "2026-06-17T10:53:16.110",
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