CVE-2026-46213
Analyzed
Analyzed - Analysis Complete
Use-After-Free in Linux Kernel HID appletb-kbd Driver
Publication date: 2026-05-28
Last updated on: 2026-06-10
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | 6.16 |
| linux | linux_kernel | 6.16 |
| linux | linux_kernel | 6.16 |
| linux | linux_kernel | 6.16 |
| linux | linux_kernel | From 6.15.6 (inc) to 6.16 (exc) |
| linux | linux_kernel | 7.1 |
| linux | linux_kernel | 7.1 |
| linux | linux_kernel | 7.1 |
| linux | linux_kernel | From 6.19 (inc) to 7.0.9 (exc) |
| linux | linux_kernel | From 6.16.1 (inc) to 6.18.32 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-416 | The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. |
