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 671F4C48BF6 for ; Wed, 21 Feb 2024 15:29:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rcoRb-0002GK-Dc; Wed, 21 Feb 2024 10:23:35 -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 1rcoL4-0001hh-KD; Wed, 21 Feb 2024 10:16:52 -0500 Received: from mgamail.intel.com ([192.198.163.16]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rco2Z-0007Tg-3P; Wed, 21 Feb 2024 09:57:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1708527463; x=1740063463; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=N/Rh861QxK57N9KeQmommhQkchtjVhc8QkT0maRgZQo=; b=K9kdT/ZlExtJEnpjVVA61JAaJbV7ZjBqIkaAz2X63vrWuqzWEMQ0GBr8 aTCaZm28kBFB34ehyf3I3SeMFhoX3uUsMmLYWG2Wu6Rb5IfSHIYHBw8Sv +Kp9vZ4RAh7IF237XrlkiUmSz/J+yKdS2TFixyBLneuNXd7REOp+ihWkW /0+vnUIr5cOqjaI9wPGaMOE7HgjD3ueKziR9daN0e95W60Dd8E4WRSgqG Y0PIJM9hycS8pdZziNjeh19qu7LUVo/mYZURHCAGVooJqgc3BygXXn+6E 9GcQTpJnNrGarBrsvokSUys6kbUqy4JgqzrTYwOV2iNHT5GSkKcMyDqJx Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="3173218" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="3173218" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Feb 2024 06:57:40 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="9752563" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.36]) by fmviesa004.fm.intel.com with ESMTP; 21 Feb 2024 06:57:33 -0800 Date: Wed, 21 Feb 2024 23:11:12 +0800 From: Zhao Liu To: Markus Armbruster Cc: Jonathan Cameron , 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?= , qemu-devel@nongnu.org, qemu-arm@nongnu.org, qemu-trivial@nongnu.org, Zhao Liu Subject: Re: [PATCH 3/6] hw/mem/cxl_type3: Fix missing ERRP_GUARD() in ct3_realize() Message-ID: References: <20240221094317.994454-1-zhao1.liu@linux.intel.com> <20240221094317.994454-4-zhao1.liu@linux.intel.com> <87zfvuuk18.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87zfvuuk18.fsf@pond.sub.org> Received-SPF: none client-ip=192.198.163.16; envelope-from=zhao1.liu@linux.intel.com; helo=mgamail.intel.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.05, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=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: , 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, Feb 21, 2024 at 12:35:47PM +0100, Markus Armbruster wrote: > Date: Wed, 21 Feb 2024 12:35:47 +0100 > From: Markus Armbruster > Subject: Re: [PATCH 3/6] hw/mem/cxl_type3: Fix missing ERRP_GUARD() in > ct3_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 ct3_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 > > ct3_realize(). > > > > Suggested-by: Markus Armbruster > > Signed-off-by: Zhao Liu > > --- > > Suggested by credit: > > Markus: Referred his explanation about ERRP_GUARD(). > > --- > > hw/mem/cxl_type3.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c > > index e8801805b90f..a3b0761f843b 100644 > > --- a/hw/mem/cxl_type3.c > > +++ b/hw/mem/cxl_type3.c > > @@ -645,6 +645,7 @@ static DOEProtocol doe_cdat_prot[] = { > > > > static void ct3_realize(PCIDevice *pci_dev, Error **errp) > > { > > + ERRP_GUARD(); > > CXLType3Dev *ct3d = CXL_TYPE3(pci_dev); > > CXLComponentState *cxl_cstate = &ct3d->cxl_cstate; > > ComponentRegisters *regs = &cxl_cstate->crb; > > The dereference is > > cxl_doe_cdat_init(cxl_cstate, errp); > if (*errp) { > goto err_free_special_ops; > } > > 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 > Thanks! 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