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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 F2DDDC433C1 for ; Tue, 23 Mar 2021 09:45:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4E99619B9 for ; Tue, 23 Mar 2021 09:45:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230233AbhCWJok (ORCPT ); Tue, 23 Mar 2021 05:44:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:55562 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230071AbhCWJoX (ORCPT ); Tue, 23 Mar 2021 05:44:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C6AC7619BD; Tue, 23 Mar 2021 09:44:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1616492663; bh=64tJTSxHuc6tooAyIwYiJx5eFO4pEzXDxnqkEmHH570=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=w/nSeRcNJHWrBA6xMlnlPTIHvIbDU4dgBEXP6fAJC3WKmoJl3+wNfl3Xu5JvUAhKD 5/lC3WfxhODSPPLsMkh+K8NaCBC4VwM13g2qO/cf2bkMIFmchB2wqjb6uQa0stvlKr kG4NLo/b+ft1wE5WB/3wa9MYk583808aTNKf3Urk= Date: Tue, 23 Mar 2021 10:44:20 +0100 From: Greg KH To: Lv Yunlong Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] usb: Add a lock when freeing data in usbtmc_disconnect Message-ID: References: <20210323092854.18911-1-lyl2019@mail.ustc.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210323092854.18911-1-lyl2019@mail.ustc.edu.cn> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, Mar 23, 2021 at 02:28:54AM -0700, Lv Yunlong wrote: > In usbtmc_disconnect, data is got from intf with the initial reference. > There is no refcount inc operation before usbmc_free_int(data). In > usbmc_free_int(data), the data may be freed. > > But later in usbtmc_disconnect, there is another put function of data. > It could cause errors in race. > > My patch adds a lock to protect kref from changing in race. > > Signed-off-by: Lv Yunlong > --- > drivers/usb/class/usbtmc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c > index 74d5a9c5238a..44f1fcabbb1e 100644 > --- a/drivers/usb/class/usbtmc.c > +++ b/drivers/usb/class/usbtmc.c > @@ -2493,8 +2493,13 @@ static void usbtmc_disconnect(struct usb_interface *intf) > usb_scuttle_anchored_urbs(&file_data->in_anchor); > } > mutex_unlock(&data->io_mutex); > + > + spinlock_t *dev_lock = &data->dev_lock; > + > + spin_lock_irq(dev_lock); > usbtmc_free_int(data); > kref_put(&data->kref, usbtmc_delete); > + spin_unlock_irq(dev_lock); > } > > static void usbtmc_draw_down(struct usbtmc_file_data *file_data) > -- > 2.25.1 You obviously did not even build this patch, let alone test it :( Please do not waste maintainer's time by not doing the proper steps when submitting patches. thanks, greg k-h