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 805A1CE79A9 for ; Tue, 19 Sep 2023 17:45:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232348AbjISRpY (ORCPT ); Tue, 19 Sep 2023 13:45:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232785AbjISRpK (ORCPT ); Tue, 19 Sep 2023 13:45:10 -0400 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F4C91992 for ; Tue, 19 Sep 2023 10:44:22 -0700 (PDT) Received: by mail-pl1-x631.google.com with SMTP id d9443c01a7336-1c3cbfa40d6so53399665ad.1 for ; Tue, 19 Sep 2023 10:44:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1695145462; x=1695750262; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=39nxaARrJPKXc7c+HVzwmiFbsNI+9PCepSFQctx9iVk=; b=fDRUogaMPNG/xyRc4PE3ESxFUqTKSB24F8iDQUk1KSc7ypf+KKRM4z7riH1EcrX4LF viMsL58hvSm9ohE9x92amPRfGl2FLamNzqTFBQZUflr0n5C/mZUNnuNR/7ys2FqlPMEB 3JePIQHqtkhpbW+qJ261Hf2COoJTsIitnZkSFb7grhizijdPzsxaBGRpjhfAfdPlkDs8 wDtnVAiVriyX11ss+KBnBQJfaMw4AvYXVNIySS28jzhT8tmT0+FWZw/tlxC7PVjNCCSA AHDBxWtA7J5Pn/mmmnCMEA18MUqDsrCNIu+FVYqDiTjV0FhOpFhipOItbVaYr0UnhpKr AR4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695145462; x=1695750262; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=39nxaARrJPKXc7c+HVzwmiFbsNI+9PCepSFQctx9iVk=; b=VxoA16VCsYfKMTPW224IueSXHqpmcbo0H7lFxprctwYu3bfMLX+uXJP7haYQZvwIwy NSG0pRIf34/37xU1F66v2ssCSEiS6FtnjKQ3DuuEFMgJsHCOzaLVlTau2LvaUf4H9iDK aNNihb81lR2egebjYuTAD/ZasEqU8Hh/sCpy/5RO0vTJR6GgtorXk/N2ikBuX8DCueMQ t0OBZ0Im+TripYsX/mZnYiazdorQnWr3LQaQO2qeRBOLrQ+U4lS1sj9dPsUvFPH4vNtN 2gZQtjQGbjo/zOEp4y8djSk6TnbQKxoouDoIqd8th3adfnHlyRvqvxOtiZt6kqkY6k5b g8Ng== X-Gm-Message-State: AOJu0Yw/v00n7uKFqFpxSm/jGIwo0RUFaY/Q2apt8jug1X7/o3WISkUI U6HUJ49/WsHyTUUXb5HCpgWOjDe7982Dmg== X-Google-Smtp-Source: AGHT+IEcuqkwqp12ee9tz6d9VYm0+9Zh4Q5t8acHgjkmMiVfN9ZeT/Qk+/9mdSXY/GXEg+uFWHlL2A== X-Received: by 2002:a17:902:c950:b0:1c5:64e1:ddd8 with SMTP id i16-20020a170902c95000b001c564e1ddd8mr149627pla.48.1695145461596; Tue, 19 Sep 2023 10:44:21 -0700 (PDT) Received: from localhost (dhcp-72-235-13-41.hawaiiantel.net. [72.235.13.41]) by smtp.gmail.com with ESMTPSA id z16-20020a170903019000b001ab2b4105ddsm10238998plg.60.2023.09.19.10.44.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Sep 2023 10:44:21 -0700 (PDT) Sender: Tejun Heo Date: Tue, 19 Sep 2023 07:44:20 -1000 From: Tejun Heo To: Zqiang Cc: jiangshanlai@gmail.com, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] workqueue: Fix UAF report by KASAN in pwq_release_workfn() Message-ID: References: <20230919081958.7071-1-qiang.zhang1211@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 19, 2023 at 07:42:39AM -1000, Tejun Heo wrote: > Hello, > > The patch looks fine but > > On Tue, Sep 19, 2023 at 04:19:58PM +0800, Zqiang wrote: > > @@ -4743,6 +4743,8 @@ struct workqueue_struct *alloc_workqueue(const char *fmt, > > wq_free_lockdep(wq); > > err_free_wq: > > free_workqueue_attrs(wq->unbound_attrs); > > Can you please add a comment here explaining why the flushing is necessary? > > > + if (wq->flags & WQ_UNBOUND) > > + kthread_flush_worker(pwq_release_worker); Hmm... also, wouldn't it be clearer to flush from alloc_and_link_pwqs() right after apply_workqueue_attrs() failed? That's the only case that requires flushing, right? Thanks. -- tejun