From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1rcoPO-0005Gf-Dg for mharc-qemu-trivial@gnu.org; Wed, 21 Feb 2024 10:21:20 -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 1rcoM9-0001hh-4F; Wed, 21 Feb 2024 10:17:57 -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 1rco1B-0007ME-4u; Wed, 21 Feb 2024 09:56:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1708527377; x=1740063377; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=GkDRFpSgEw4Jc9eQg/w5fzMP57UNmwkGjsPiSjtncj0=; b=ctcChPA3oBeHTYSiHnl5bvKZFvKnF0D5fgaHihfmnae8Fra7benpp9ND fVSxhro6WvWFwacqeDLbGVZCtlehEJMQdcm6q6q6WdER0E84PoArzKHJE V+o9xuZxtLDnNvfIP1F8mPRP4Q4p33Ohrx4r4zt+acxTrL2Wy61b8VVd6 qQCnVB4W+/1bVs4W0mlhIoO1sUULLA7sp+kkC/7b2jcIEftBaK4LgafoI OED7J7D83SU/EceoNqR/wAmxU6PTWWgfQ9e6rqNfaTxRL8Rhd8dTbI2kT NF9cNFyrpV1UjGqf3CFwVTFEec03P3CpBEKI5NnDM9C68Gxa5yv/pVNl9 w==; X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="3173102" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="3173102" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Feb 2024 06:56:15 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="9782187" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.36]) by fmviesa005.fm.intel.com with ESMTP; 21 Feb 2024 06:56:11 -0800 Date: Wed, 21 Feb 2024 23:09:49 +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 5/6] hw/pci-bridge/cxl_upstream: Fix missing ERRP_GUARD() in cxl_usp_realize() Message-ID: References: <20240221094317.994454-1-zhao1.liu@linux.intel.com> <20240221094317.994454-6-zhao1.liu@linux.intel.com> <87le7eujdx.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87le7eujdx.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-trivial@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Feb 2024 15:18:14 -0000 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 > 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