5.4-stable review patch. If anyone has any objections, please let me know.
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From: Yuhao Jiang danisjiang@gmail.com
commit 8f067aa59430266386b83c18b983ca583faa6a11 upstream.
The switch_brightness_work delayed work accesses device->brightness and device->backlight, freed by acpi_video_dev_unregister_backlight() during device removal.
If the work executes after acpi_video_bus_unregister_backlight() frees these resources, it causes a use-after-free when acpi_video_switch_brightness() dereferences device->brightness or device->backlight.
Fix this by calling cancel_delayed_work_sync() for each device's switch_brightness_work in acpi_video_bus_remove_notify_handler() after removing the notify handler that queues the work. This ensures the work completes before the memory is freed.
Fixes: 8ab58e8e7e097 ("ACPI / video: Fix backlight taking 2 steps on a brightness up/down keypress") Cc: All applicable stable@vger.kernel.org Signed-off-by: Yuhao Jiang danisjiang@gmail.com Reviewed-by: Hans de Goede hansg@kernel.org [ rjw: Changelog edit ] Link: https://patch.msgid.link/20251022200704.2655507-1-danisjiang@gmail.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/acpi_video.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -2024,8 +2024,10 @@ static void acpi_video_bus_remove_notify struct acpi_video_device *dev;
mutex_lock(&video->device_list_lock); - list_for_each_entry(dev, &video->video_device_list, entry) + list_for_each_entry(dev, &video->video_device_list, entry) { acpi_video_dev_remove_notify_handler(dev); + cancel_delayed_work_sync(&dev->switch_brightness_work); + } mutex_unlock(&video->device_list_lock);
acpi_video_bus_stop_devices(video);