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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 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 26EA4C433DF for ; Wed, 12 Aug 2020 08:02:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 073DA20768 for ; Wed, 12 Aug 2020 08:02:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726680AbgHLIC5 (ORCPT ); Wed, 12 Aug 2020 04:02:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:34134 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726479AbgHLIC5 (ORCPT ); Wed, 12 Aug 2020 04:02:57 -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 2EF0BAEA8; Wed, 12 Aug 2020 08:03:17 +0000 (UTC) Message-ID: <1597219371.28022.6.camel@suse.com> Subject: Re: [PATCH] USB: cdc-wdm: Remove unsafe wdm_flush(). From: Oliver Neukum To: Tetsuo Handa , Greg Kroah-Hartman Cc: Andrey Konovalov , Alan Stern , Colin Ian King , Arnd Bergmann , Linus Torvalds , linux-usb@vger.kernel.org, syzbot Date: Wed, 12 Aug 2020 10:02:51 +0200 In-Reply-To: <1597188375-4787-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> References: <1597188375-4787-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Am Mittwoch, den 12.08.2020, 08:26 +0900 schrieb Tetsuo Handa: > syzbot is reporting hung task at wdm_flush() [1], for there is a circular > dependency that wdm_flush() from flip_close() for /dev/cdc-wdm0 forever > waits for /dev/raw-gadget to be closed while close() for /dev/raw-gadget > cannot be called unless close() for /dev/cdc-wdm0 completes. > > It turned out that wdm_flush() is broken in multiple aspects. Sorry, this seems to be a miscommunication. I was under the impression that you were testing patches. I will push them upstream. You cannot just remove flush() without impairing error handling. Regards Oliver Nacked-by: Oliver Neukum