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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 890EAC43381 for ; Mon, 18 Feb 2019 10:10:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F6A72147A for ; Mon, 18 Feb 2019 10:10:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729796AbfBRKKt (ORCPT ); Mon, 18 Feb 2019 05:10:49 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:39176 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727004AbfBRKKs (ORCPT ); Mon, 18 Feb 2019 05:10:48 -0500 Received: from fsav405.sakura.ne.jp (fsav405.sakura.ne.jp [133.242.250.104]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x1IAAXEm049673; Mon, 18 Feb 2019 19:10:33 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav405.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp); Mon, 18 Feb 2019 19:10:33 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp) Received: from [192.168.1.8] (softbank126126163036.bbtec.net [126.126.163.36]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x1IAAN3U049606 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Mon, 18 Feb 2019 19:10:32 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH (resend)] Input: uinput - Set name/phys to NULL before kfree(). To: Dmitry Torokhov Cc: rydberg@bitmath.org, syzbot , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <0000000000009ce64e0574fe896e@google.com> <47d5fdbe-120e-cf42-106f-b0cc0f2feb49@I-love.SAKURA.ne.jp> <20190217210713.GA145509@dtor-ws> From: Tetsuo Handa Message-ID: <722c14a1-78cd-14b6-59ef-ba0d6fc82cb1@i-love.sakura.ne.jp> Date: Mon, 18 Feb 2019 19:10:23 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190217210713.GA145509@dtor-ws> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thank you for responding. On 2019/02/18 6:07, Dmitry Torokhov wrote: > The commit tries to send final uevent for objects for which "add" uevent > has been sent, but not "remove" event. However in uinput (and general > input case) we always take care of sending uevent at unregister, and do > not expect to have uevent sent out at the final "put" time. Then, we want to keep dev->name and dev->phys when calling "unregister" time. > > I believe the real fix is to have kobj->state_remove_uevent_sent be set > to true as soon as we enter kobject_uevent(kobj, KOBJ_REMOVE) so that > it is being set even if memory allocation fails. Doing anything else may > violate expectations of subsystem owning the kobject. If we want to keep dev->name and dev->phys when calling "unregister" time, we could do something like below. Does calling kobject_uevent(KOBJ_REMOVE) without dev->name and dev->phys (to some degree) help (compared to not triggering kobject_uevent(KOBJ_REMOVE) at all) ? diff --git a/drivers/input/input.c b/drivers/input/input.c index 3304aaa..da39a23 100644 --- a/drivers/input/input.c +++ b/drivers/input/input.c @@ -1587,6 +1587,7 @@ static int input_dev_uevent(struct device *device, struct kobj_uevent_env *env) { struct input_dev *dev = to_input_dev(device); + rcu_read_lock(); INPUT_ADD_HOTPLUG_VAR("PRODUCT=%x/%x/%x/%x", dev->id.bustype, dev->id.vendor, dev->id.product, dev->id.version); @@ -1618,6 +1619,7 @@ static int input_dev_uevent(struct device *device, struct kobj_uevent_env *env) INPUT_ADD_HOTPLUG_BM_VAR("SW=", dev->swbit, SW_MAX); INPUT_ADD_HOTPLUG_MODALIAS_VAR(dev); + rcu_read_unlock(); return 0; } diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c index 26ec603f..6689312 100644 --- a/drivers/input/misc/uinput.c +++ b/drivers/input/misc/uinput.c @@ -308,9 +308,12 @@ static void uinput_destroy_device(struct uinput_device *udev) } else { input_free_device(dev); } + dev->name = NULL; + dev->phys = NULL; + udev->dev = NULL; + synchronize_rcu(); kfree(name); kfree(phys); - udev->dev = NULL; } }