From 69ef9bc54715fb1cb7786ada15774e469e822209 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sat, 9 Feb 2019 00:38:45 +0100 Subject: auxdisplay: ht16k33: fix potential user-after-free on module unload On module unload/remove, we need to ensure that work does not run after we have freed resources. Concretely, cancel_delayed_work() may return while the callback function is still running. From kernel/workqueue.c: The work callback function may still be running on return, unless it returns true and the work doesn't re-arm itself. Explicitly flush or use cancel_delayed_work_sync() to wait on it. Link: https://lore.kernel.org/lkml/20190204220952.30761-1-TheSven73@googlemail.com/ Reported-by: Sven Van Asbroeck Reviewed-by: Dmitry Torokhov Reviewed-by: Sven Van Asbroeck Acked-by: Robin van der Gracht Signed-off-by: Miguel Ojeda --- drivers/auxdisplay/ht16k33.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c index a43276c76fc6..21393ec3b9a4 100644 --- a/drivers/auxdisplay/ht16k33.c +++ b/drivers/auxdisplay/ht16k33.c @@ -509,7 +509,7 @@ static int ht16k33_remove(struct i2c_client *client) struct ht16k33_priv *priv = i2c_get_clientdata(client); struct ht16k33_fbdev *fbdev = &priv->fbdev; - cancel_delayed_work(&fbdev->work); + cancel_delayed_work_sync(&fbdev->work); unregister_framebuffer(fbdev->info); framebuffer_release(fbdev->info); free_page((unsigned long) fbdev->buffer); -- cgit v1.2.3-59-g8ed1b