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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 643AEC5478C for ; Mon, 26 Feb 2024 15:55:07 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1redJX-0001ZO-F7; Mon, 26 Feb 2024 10:54:47 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1redJW-0001X2-IT; Mon, 26 Feb 2024 10:54:46 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1redJU-0003iu-RC; Mon, 26 Feb 2024 10:54:46 -0500 Received: from mail.maildlp.com (unknown [172.18.186.216]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Tk4nq4RQcz6897v; Mon, 26 Feb 2024 23:50:23 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 9543F140A78; Mon, 26 Feb 2024 23:54:42 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Mon, 26 Feb 2024 15:54:42 +0000 Date: Mon, 26 Feb 2024 15:54:40 +0000 To: Zhao Liu CC: Markus Armbruster , Fan Ni , Laurent Vivier , Alistair Francis , "Edgar E . Iglesias" , Peter Maydell , "Michael S . Tsirkin" , Marcel Apfelbaum , "Alex Williamson" , "=?ISO-8859-1?Q?C=E9dric?= Le Goater" , Philippe =?ISO-8859-1?Q?Mathieu-Daud=E9?= , , , , Zhao Liu Subject: Re: [PATCH 5/6] hw/pci-bridge/cxl_upstream: Fix missing ERRP_GUARD() in cxl_usp_realize() Message-ID: <20240226155440.0000183f@Huawei.com> In-Reply-To: References: <20240221094317.994454-1-zhao1.liu@linux.intel.com> <20240221094317.994454-6-zhao1.liu@linux.intel.com> <87le7eujdx.fsf@pond.sub.org> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100002.china.huawei.com (7.191.160.241) To lhrpeml500005.china.huawei.com (7.191.163.240) Received-SPF: pass client-ip=185.176.79.56; envelope-from=jonathan.cameron@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-to: Jonathan Cameron From: Jonathan Cameron via Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, 21 Feb 2024 23:09:49 +0800 Zhao Liu wrote: > On Wed, Feb 21, 2024 at 12:49:46PM +0100, Markus Armbruster wrote: > > Date: Wed, 21 Feb 2024 12:49:46 +0100 > > From: Markus Armbruster > > Subject: Re: [PATCH 5/6] hw/pci-bridge/cxl_upstream: Fix missing > > ERRP_GUARD() in cxl_usp_realize() > > > > Zhao Liu writes: > > > > > From: Zhao Liu > > > > > > As the comment in qapi/error, dereferencing @errp requires > > > ERRP_GUARD(): > > > > > > * = Why, when and how to use ERRP_GUARD() = > > > * > > > * Without ERRP_GUARD(), use of the @errp parameter is restricted: > > > * - It must not be dereferenced, because it may be null. > > > * - It should not be passed to error_prepend() or > > > * error_append_hint(), because that doesn't work with &error_fatal. > > > * ERRP_GUARD() lifts these restrictions. > > > * > > > * To use ERRP_GUARD(), add it right at the beginning of the function. > > > * @errp can then be used without worrying about the argument being > > > * NULL or &error_fatal. > > > * > > > * Using it when it's not needed is safe, but please avoid cluttering > > > * the source with useless code. > > > > > > Currently, since cxl_usp_realize() - as a PCIDeviceClass.realize() > > > method - doesn't get the NULL errp parameter, it doesn't trigger the > > > dereference issue. > > > > > > To follow the requirement of errp, add missing ERRP_GUARD() in > > > cxl_usp_realize()(). > > > > > > Suggested-by: Markus Armbruster > > > Signed-off-by: Zhao Liu > > > --- > > > Suggested by credit: > > > Markus: Referred his explanation about ERRP_GUARD(). > > > --- > > > hw/pci-bridge/cxl_upstream.c | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/hw/pci-bridge/cxl_upstream.c b/hw/pci-bridge/cxl_upstream.c > > > index e87eb4017713..03d123cca0ef 100644 > > > --- a/hw/pci-bridge/cxl_upstream.c > > > +++ b/hw/pci-bridge/cxl_upstream.c > > > @@ -289,6 +289,7 @@ static void free_default_cdat_table(CDATSubHeader **cdat_table, int num, > > > > > > static void cxl_usp_realize(PCIDevice *d, Error **errp) > > > { > > > + ERRP_GUARD(); > > > PCIEPort *p = PCIE_PORT(d); > > > CXLUpstreamPort *usp = CXL_USP(d); > > > CXLComponentState *cxl_cstate = &usp->cxl_cstate; > > > > The dereference is > > > > cxl_doe_cdat_init(cxl_cstate, errp); > > if (*errp) { > > goto err_cap; > > } > > > > As noted in review of PATCH 3, we check *errp, because > > cxl_doe_cdat_init() returns void. Could be improved to return bool, > > along with its callees ct3_load_cdat() and ct3_build_cdat(), but that's > > a slightly more ambitious cleanup, so > > > > Reviewed-by: Markus Armbruster > > Acked-by: Jonathan Cameron > > Thanks! It's a good idea and I can continue to consider such the cleanup > in the follow up. > > Will also add the dereference description in commit message to make > review easier. > > Regards, > Zhao >