From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 109CCC433F5 for ; Thu, 17 Feb 2022 12:05:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240250AbiBQMGG (ORCPT ); Thu, 17 Feb 2022 07:06:06 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:60932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232390AbiBQMGC (ORCPT ); Thu, 17 Feb 2022 07:06:02 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2B796577; Thu, 17 Feb 2022 04:05:47 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 84EADB8216E; Thu, 17 Feb 2022 12:05:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25CD2C340E8; Thu, 17 Feb 2022 12:05:43 +0000 (UTC) Message-ID: Date: Thu, 17 Feb 2022 13:05:42 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH] media: hdpvr: call flush_work only if initialized Content-Language: en-US To: Dongliang Mu , Mauro Carvalho Chehab , Dongliang Mu Cc: syzkaller , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220217043950.749343-1-dzm91@hust.edu.cn> From: Hans Verkuil In-Reply-To: <20220217043950.749343-1-dzm91@hust.edu.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/02/2022 05:39, Dongliang Mu wrote: > From: Dongliang Mu > > flush_work will throw one WARN if worker->func is NULL. So we should always > initialize one worker before calling flush_work. When hdpvr_probe does not > initialize its worker, the hdpvr_disconnect will encounter one WARN. The > stack trace is in the following: > > hdpvr_disconnect+0xb8/0xf2 drivers/media/usb/hdpvr/hdpvr-core.c:425 > usb_unbind_interface+0xbf/0x3a0 drivers/usb/core/driver.c:458 > __device_release_driver drivers/base/dd.c:1206 [inline] > device_release_driver_internal+0x22a/0x230 drivers/base/dd.c:1237 > bus_remove_device+0x108/0x160 drivers/base/bus.c:529 > device_del+0x1fe/0x510 drivers/base/core.c:3592 > usb_disable_device+0xd1/0x1d0 drivers/usb/core/message.c:1419 > usb_disconnect+0x109/0x330 drivers/usb/core/hub.c:2228 > > Fix this by adding a sanity check of the worker before flush_work. > > Reported-by: syzkaller > Signed-off-by: Dongliang Mu > --- > drivers/media/usb/hdpvr/hdpvr-core.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/usb/hdpvr/hdpvr-core.c b/drivers/media/usb/hdpvr/hdpvr-core.c > index 52e05a69c46e..d102b459d45d 100644 > --- a/drivers/media/usb/hdpvr/hdpvr-core.c > +++ b/drivers/media/usb/hdpvr/hdpvr-core.c > @@ -422,7 +422,8 @@ static void hdpvr_disconnect(struct usb_interface *interface) > mutex_unlock(&dev->io_mutex); > v4l2_device_disconnect(&dev->v4l2_dev); > msleep(100); > - flush_work(&dev->worker); > + if (dev->worker.func) > + flush_work(&dev->worker); I don't think this is the right fix. Instead, move the INIT_WORK line from hdpvr_start_streaming() to hdpvr_register_videodev(). That should initialize the worker struct from the start instead of only when you start streaming, as is the case today. Can you try that? Regards, Hans > mutex_lock(&dev->io_mutex); > hdpvr_cancel_queue(dev); > mutex_unlock(&dev->io_mutex);