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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 5C39CC433E7 for ; Fri, 9 Oct 2020 05:39:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 284C122240 for ; Fri, 9 Oct 2020 05:39:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731565AbgJIFjC convert rfc822-to-8bit (ORCPT ); Fri, 9 Oct 2020 01:39:02 -0400 Received: from mx2.suse.de ([195.135.220.15]:43540 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729347AbgJIFjC (ORCPT ); Fri, 9 Oct 2020 01:39:02 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 135A7ACAC; Fri, 9 Oct 2020 05:39:00 +0000 (UTC) From: Nicolai Stange To: Taehee Yoo Cc: Johannes Berg , David Laight , "davem\@davemloft.net" , "kuba\@kernel.org" , "netdev\@vger.kernel.org" , Nicolai Stange , "linux-wireless\@vger.kernel.org" , "wil6210\@qti.qualcomm.com" , "brcm80211-dev-list\@cypress.com" , "b43-dev\@lists.infradead.org" , "linux-bluetooth\@vger.kernel.org" Subject: Re: [PATCH net 000/117] net: avoid to remove module when its debugfs is being used References: <20201008155048.17679-1-ap420073@gmail.com> <1cbb69d83188424e99b2d2482848ae64@AcuMS.aculab.com> <62f6c2bd11ed8b25c1cd4462ebc6db870adc4229.camel@sipsolutions.net> Date: Fri, 09 Oct 2020 07:38:59 +0200 In-Reply-To: (Taehee Yoo's message of "Fri, 9 Oct 2020 01:37:26 +0900") Message-ID: <87r1q8gdqk.fsf@suse.de> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org Taehee Yoo writes: > On Fri, 9 Oct 2020 at 01:14, Johannes Berg wrote: > On Thu, 2020-10-08 at 15:59 +0000, David Laight wrote: > >> From: Taehee Yoo >> > Sent: 08 October 2020 16:49 >> > >> > When debugfs file is opened, its module should not be removed until >> > it's closed. >> > Because debugfs internally uses the module's data. >> > So, it could access freed memory. Yes, the file_operations' ->release() to be more specific -- that's not covered by debugfs' proxy fops. >> > In order to avoid panic, it just sets .owner to THIS_MODULE. >> > So that all modules will be held when its debugfs file is opened. >> >> Can't you fix it in common code? > >> Yeah I was just wondering that too - weren't the proxy_fops even already >> intended to fix this? > > I didn't try to fix this issue in the common code(debugfs). > Because I thought It's a typical pattern of panic and THIS_MODULE > can fix it clearly. > So I couldn't think there is a root reason in the common code. That's correct, ->owner should get set properly, c.f. my other mail in this thread. Thanks, Nicolai -- SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg), GF: Felix Imendörffer