From: Yuhao Jiang Date: Wed, 22 Oct 2025 20:07:04 +0000 (-0500) Subject: ACPI: video: Fix use-after-free in acpi_video_switch_brightness() X-Git-Tag: v6.18-rc4~21^2^3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8f067aa59430266386b83c18b983ca583faa6a11;p=thirdparty%2Fkernel%2Fstable.git ACPI: video: Fix use-after-free in acpi_video_switch_brightness() 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 Signed-off-by: Yuhao Jiang Reviewed-by: Hans de Goede [ rjw: Changelog edit ] Link: https://patch.msgid.link/20251022200704.2655507-1-danisjiang@gmail.com Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index 103f296615762..be8e7e18abcab 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -1959,8 +1959,10 @@ static void acpi_video_bus_remove_notify_handler(struct acpi_video_bus *video) 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);