Bug 2436766 (CVE-2026-23101)

Summary: CVE-2026-23101 kernel: leds: led-class: Only Add LED to leds_list when it is fully ready
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A race condition vulnerability was found in the Linux kernel's LED class subsystem. When registering LEDs, the device is added to leds_list before led_init_core() initializes the set_brightness_work workqueue. If a trigger registration occurs during this window, led_set_brightness() attempts to queue an uninitialized work structure, triggering a warning in __flush_work() and potentially causing undefined behavior.
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Description OSIDB Bzimport 2026-02-04 17:02:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

leds: led-class: Only Add LED to leds_list when it is fully ready

Before this change the LED was added to leds_list before led_init_core()
gets called adding it the list before led_classdev.set_brightness_work gets
initialized.

This leaves a window where led_trigger_register() of a LED's default
trigger will call led_trigger_set() which calls led_set_brightness()
which in turn will end up queueing the *uninitialized*
led_classdev.set_brightness_work.

This race gets hit by the lenovo-thinkpad-t14s EC driver which registers
2 LEDs with a default trigger provided by snd_ctl_led.ko in quick
succession. The first led_classdev_register() causes an async modprobe of
snd_ctl_led to run and that async modprobe manages to exactly hit
the window where the second LED is on the leds_list without led_init_core()
being called for it, resulting in:

 ------------[ cut here ]------------
 WARNING: CPU: 11 PID: 5608 at kernel/workqueue.c:4234 __flush_work+0x344/0x390
 Hardware name: LENOVO 21N2S01F0B/21N2S01F0B, BIOS N42ET93W (2.23 ) 09/01/2025
 ...
 Call trace:
  __flush_work+0x344/0x390 (P)
  flush_work+0x2c/0x50
  led_trigger_set+0x1c8/0x340
  led_trigger_register+0x17c/0x1c0
  led_trigger_register_simple+0x84/0xe8
  snd_ctl_led_init+0x40/0xf88 [snd_ctl_led]
  do_one_initcall+0x5c/0x318
  do_init_module+0x9c/0x2b8
  load_module+0x7e0/0x998

Close the race window by moving the adding of the LED to leds_list to
after the led_init_core() call.
Comment 1 Jon Moroney 2026-02-05 00:51:26 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026020428-CVE-2026-23101-47e0@gregkh/T