kernel/linux.git/drivers/leds/led-class.c, branch v6.1.168

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

2026-02-06T15:44:11+00:00

commit d1883cefd31752f0504b94c3bcfa1f6d511d6e87 upstream. 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. Cc: stable@vger.kernel.org Fixes: d23a22a74fde ("leds: delay led_set_brightness if stopping soft-blink") Signed-off-by: Hans de Goede Reviewed-by: Sebastian Reichel Link: https://patch.msgid.link/20251211163727.366441-1-johannes.goede@oss.qualcomm.com Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman

leds: Replace all non-returning strlcpy with strscpy

2026-01-11T14:18:13+00:00

[ Upstream commit bf4a35e9201d30b63a8d276797d6ecfaa596ccd3 ] strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated [1]. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). No return values were used, so direct replacement is safe. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 Signed-off-by: Azeem Shaikh Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20230523021451.2406362-1-azeemshaikh38@gmail.com Signed-off-by: Lee Jones Stable-dep-of: ccc35ff2fd29 ("leds: spi-byte: Use devm_led_classdev_register_ext()") Signed-off-by: Sasha Levin

leds: class: Protect brightness_show() with led_cdev->led_access mutex

2024-12-14T18:54:46+00:00

[ Upstream commit 4ca7cd938725a4050dcd62ae9472e931d603118d ] There is NULL pointer issue observed if from Process A where hid device being added which results in adding a led_cdev addition and later a another call to access of led_cdev attribute from Process B can result in NULL pointer issue. Use mutex led_cdev->led_access to protect access to led->cdev and its attribute inside brightness_show() and max_brightness_show() and also update the comment for mutex that it should be used to protect the led class device fields. Process A Process B kthread+0x114 worker_thread+0x244 process_scheduled_works+0x248 uhid_device_add_worker+0x24 hid_add_device+0x120 device_add+0x268 bus_probe_device+0x94 device_initial_probe+0x14 __device_attach+0xfc bus_for_each_drv+0x10c __device_attach_driver+0x14c driver_probe_device+0x3c __driver_probe_device+0xa0 really_probe+0x190 hid_device_probe+0x130 ps_probe+0x990 ps_led_register+0x94 devm_led_classdev_register_ext+0x58 led_classdev_register_ext+0x1f8 device_create_with_groups+0x48 device_create_groups_vargs+0xc8 device_add+0x244 kobject_uevent+0x14 kobject_uevent_env[jt]+0x224 mutex_unlock[jt]+0xc4 __mutex_unlock_slowpath+0xd4 wake_up_q+0x70 try_to_wake_up[jt]+0x48c preempt_schedule_common+0x28 __schedule+0x628 __switch_to+0x174 el0t_64_sync+0x1a8/0x1ac el0t_64_sync_handler+0x68/0xbc el0_svc+0x38/0x68 do_el0_svc+0x1c/0x28 el0_svc_common+0x80/0xe0 invoke_syscall+0x58/0x114 __arm64_sys_read+0x1c/0x2c ksys_read+0x78/0xe8 vfs_read+0x1e0/0x2c8 kernfs_fop_read_iter+0x68/0x1b4 seq_read_iter+0x158/0x4ec kernfs_seq_show+0x44/0x54 sysfs_kf_seq_show+0xb4/0x130 dev_attr_show+0x38/0x74 brightness_show+0x20/0x4c dualshock4_led_get_brightness+0xc/0x74 [ 3313.874295][ T4013] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000060 [ 3313.874301][ T4013] Mem abort info: [ 3313.874303][ T4013] ESR = 0x0000000096000006 [ 3313.874305][ T4013] EC = 0x25: DABT (current EL), IL = 32 bits [ 3313.874307][ T4013] SET = 0, FnV = 0 [ 3313.874309][ T4013] EA = 0, S1PTW = 0 [ 3313.874311][ T4013] FSC = 0x06: level 2 translation fault [ 3313.874313][ T4013] Data abort info: [ 3313.874314][ T4013] ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000 [ 3313.874316][ T4013] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 3313.874318][ T4013] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 3313.874320][ T4013] user pgtable: 4k pages, 39-bit VAs, pgdp=00000008f2b0a000 .. [ 3313.874332][ T4013] Dumping ftrace buffer: [ 3313.874334][ T4013] (ftrace buffer empty) .. .. [ dd3313.874639][ T4013] CPU: 6 PID: 4013 Comm: InputReader [ 3313.874648][ T4013] pc : dualshock4_led_get_brightness+0xc/0x74 [ 3313.874653][ T4013] lr : led_update_brightness+0x38/0x60 [ 3313.874656][ T4013] sp : ffffffc0b910bbd0 .. .. [ 3313.874685][ T4013] Call trace: [ 3313.874687][ T4013] dualshock4_led_get_brightness+0xc/0x74 [ 3313.874690][ T4013] brightness_show+0x20/0x4c [ 3313.874692][ T4013] dev_attr_show+0x38/0x74 [ 3313.874696][ T4013] sysfs_kf_seq_show+0xb4/0x130 [ 3313.874700][ T4013] kernfs_seq_show+0x44/0x54 [ 3313.874703][ T4013] seq_read_iter+0x158/0x4ec [ 3313.874705][ T4013] kernfs_fop_read_iter+0x68/0x1b4 [ 3313.874708][ T4013] vfs_read+0x1e0/0x2c8 [ 3313.874711][ T4013] ksys_read+0x78/0xe8 [ 3313.874714][ T4013] __arm64_sys_read+0x1c/0x2c [ 3313.874718][ T4013] invoke_syscall+0x58/0x114 [ 3313.874721][ T4013] el0_svc_common+0x80/0xe0 [ 3313.874724][ T4013] do_el0_svc+0x1c/0x28 [ 3313.874727][ T4013] el0_svc+0x38/0x68 [ 3313.874730][ T4013] el0t_64_sync_handler+0x68/0xbc [ 3313.874732][ T4013] el0t_64_sync+0x1a8/0x1ac Signed-off-by: Mukesh Ojha Reviewed-by: Anish Kumar Link: https://lore.kernel.org/r/20241103160527.82487-1-quic_mojha@quicinc.com Signed-off-by: Lee Jones Signed-off-by: Sasha Levin

Revert "leds: led-core: Fix refcount leak in of_led_get()"

2024-08-03T06:49:14+00:00

[ Upstream commit 940b27161afc6ec53fc66245a4fb3518394cdc92 ] This reverts commit da1afe8e6099980fe1e2fd7436dca284af9d3f29. Commit 699a8c7c4bd3 ("leds: Add of_led_get() and led_put()"), introduced in 5.5, added of_led_get() and led_put() but missed a put_device() in led_put(), thus creating a leak in case the consumer device is removed. Arguably device removal was not very popular, so this went apparently unnoticed until 2022. In January 2023 two different patches got merged to fix the same bug: - commit da1afe8e6099 ("leds: led-core: Fix refcount leak in of_led_get()") - commit 445110941eb9 ("leds: led-class: Add missing put_device() to led_put()") They fix the bug in two different ways, which creates no patch conflicts, and both were merged in v6.2. The result is that now there is one more put_device() than get_device()s, instead of one less. Arguably device removal is not very popular yet, so this apparently hasn't been noticed as well up to now. But it blew up here while I'm working with device tree overlay insertion and removal. The symptom is an apparently unrelated list of oopses on device removal, with reasons: kernfs: can not remove 'uevent', no directory kernfs: can not remove 'brightness', no directory kernfs: can not remove 'max_brightness', no directory ... Here sysfs fails removing attribute files, which is because the device name changed and so the sysfs path. This is because the device name string got corrupted, which is because it got freed too early and its memory reused. Different symptoms could appear in different use cases. Fix by removing one of the two fixes. The choice was to remove commit da1afe8e6099 because: * it is calling put_device() inside of_led_get() just after getting the device, thus it is basically not refcounting the LED device at all during its entire lifetime * it does not add a corresponding put_device() in led_get(), so it fixes only the OF case The other fix (445110941eb9) is adding the put_device() in led_put() so it covers the entire lifetime, and it works even in the non-DT case. Fixes: da1afe8e6099 ("leds: led-core: Fix refcount leak in of_led_get()") Co-developed-by: Hervé Codina Signed-off-by: Hervé Codina Signed-off-by: Luca Ceresoli Link: https://lore.kernel.org/r/20240625-led-class-device-leak-v2-1-75fdccf47421@bootlin.com Signed-off-by: Lee Jones Signed-off-by: Sasha Levin

leds: led-core: Fix refcount leak in of_led_get()

2023-03-10T08:33:26+00:00

[ Upstream commit da1afe8e6099980fe1e2fd7436dca284af9d3f29 ] class_find_device_by_of_node() calls class_find_device(), it will take the reference, use the put_device() to drop the reference when not need anymore. Fixes: 699a8c7c4bd3 ("leds: Add of_led_get() and led_put()") Signed-off-by: Miaoqian Lin Signed-off-by: Lee Jones Link: https://lore.kernel.org/r/20221220121807.1543790-1-linmq006@gmail.com Signed-off-by: Sasha Levin

leds: led-class: Add missing put_device() to led_put()

2023-03-10T08:32:57+00:00

[ Upstream commit 445110941eb94709216363f9d807d2508e64abd7 ] led_put() is used to "undo" a successful of_led_get() call, of_led_get() uses class_find_device_by_of_node() which returns a reference to the device which must be free-ed with put_device() when the caller is done with it. Add a put_device() call to led_put() to free the reference returned by class_find_device_by_of_node(). And also add a put_device() in the error-exit case of try_module_get() failing. Fixes: 699a8c7c4bd3 ("leds: Add of_led_get() and led_put()") Reviewed-by: Andy Shevchenko Reviewed-by: Linus Walleij Signed-off-by: Hans de Goede Signed-off-by: Lee Jones Link: https://lore.kernel.org/r/20230120114524.408368-2-hdegoede@redhat.com Signed-off-by: Sasha Levin

leds: led-core: Update fwnode with device_set_node

2022-01-12T18:43:14+00:00

Update a newly created device's fwnode and of_node pointers using the recently added device_set_node helper. This keeps some firmware node specifics out of led-class and should help tracking future changes regarding device firmware node updates. Signed-off-by: Sander Vanheule Signed-off-by: Pavel Machek

leds: leds-core: Implement the retain-state-shutdown property

2021-08-20T09:00:06+00:00

Read the retain-state-shutdown device tree property to set the existing LED_RETAIN_AT_SHUTDOWN flag. Then check the flag when unregistering, and if set, don't set the brightness to OFF. This is useful for systems that want to keep the HW state of the LED across reboots. Signed-off-by: Eddie James Signed-off-by: Pavel Machek

leds: class: The -ENOTSUPP should never be seen by user space

2021-05-28T09:59:59+00:00

Drop the bogus error code and let of_led_get() to take care about absent of_node. Fixes: e389240ad992 ("leds: Add managed API to get a LED from a device driver") Cc: Jean-Jacques Hiblot Signed-off-by: Andy Shevchenko Signed-off-by: Pavel Machek

leds: led-class: Fix incorrectly documented param 'dev'

2021-05-28T09:38:54+00:00

Fixes the following W=1 kernel build warning(s): drivers/leds/led-class.c:521: warning: Function parameter or member 'dev' not described in 'devm_led_classdev_unregister' drivers/leds/led-class.c:521: warning: Excess function parameter 'parent' description in 'devm_led_classdev_unregister' Cc: Pavel Machek Cc: John Lenz Cc: Richard Purdie Cc: linux-leds@vger.kernel.org Signed-off-by: Lee Jones Signed-off-by: Pavel Machek