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[76.150.86.52]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-430d07a8725sm51436015ab.21.2025.10.21.21.09.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Oct 2025 21:09:02 -0700 (PDT) From: Yuhao Jiang To: "Rafael J . Wysocki" Cc: Len Brown , Hans de Goede , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Yuhao Jiang Subject: [PATCH] ACPI: video: Fix use-after-free in acpi_video_bus_put_devices() Date: Tue, 21 Oct 2025 23:08:58 -0500 Message-Id: <20251022040859.2102914-1-danisjiang@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The code contains a use-after-free vulnerability due to missing cancellation of delayed work during device removal. Specifically, in acpi_video_bus_remove(), the function acpi_video_bus_put_devices() is called, which frees all acpi_video_device structures without cancelling the associated delayed work (switch_brightness_work). This work is scheduled via brightness_switch_event() in response to ACPI events (e.g., brightness key presses) with a 100ms delay. If the work is pending when the device is removed, it may execute after the memory is freed, leading to use-after-free when the work function acpi_video_switch_brightness() accesses the device structure. Fix this by calling cancel_delayed_work_sync() before freeing each acpi_video_device to ensure the work is fully completed before the memory is released. Fixes: 67b662e189f46 ("ACPI / video: seperate backlight control and event i= nterface") Cc: stable@vger.kernel.org Signed-off-by: Yuhao Jiang --- drivers/acpi/acpi_video.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index 103f29661576..5b80f87e078f 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -1974,6 +1974,7 @@ static int acpi_video_bus_put_devices(struct acpi_vid= eo_bus *video) =20 mutex_lock(&video->device_list_lock); list_for_each_entry_safe(dev, next, &video->video_device_list, entry) { + cancel_delayed_work_sync(&dev->switch_brightness_work); list_del(&dev->entry); kfree(dev); } --=20 2.34.1