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 08CE8C48BF6 for ; Wed, 21 Feb 2024 15:24:30 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rcoRP-0001kv-16; Wed, 21 Feb 2024 10:23:23 -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 1rcoKz-0000nB-7G; Wed, 21 Feb 2024 10:16:46 -0500 Received: from mgamail.intel.com ([192.198.163.15]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rcnwv-0006r8-V3; Wed, 21 Feb 2024 09:52:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1708527114; x=1740063114; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=4ak9kaacz/hdfQkekQ6mF744vrtw9wcS9x6gihIV+eE=; b=gjdx9/qC4J6PUSkGs7xJLsANmqsjO2md3l/xkYgmvSBBV3CqkX2KrYPp nnPKhJSXgQ3VC5OwDI/nbrC83KP6ISCVMrj1XrNFr3QOi3U5CeyX8183F kpA85/hbqWIzCecowZtWm7A4KOtaBZoVeFhxW3JmUnmtegcIXIfTyTZ1Y qkhzvrUC3YPBhD1UP6S1U+uTVuRFtsI8eGqnJK0F6dy51tS1kd7dX6+ds w+gR3bQiiHu6cZU1yh+ja5MEP3JPldBct7caOCBiI9MLNCmmZMb8koD99 6vTD76fyC6/SWBcGK9HwdLYAxoijBlHte0PMx31P3cxnbU4SM6fdVtThu w==; X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="2827374" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="2827374" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Feb 2024 06:51:51 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="936655259" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="936655259" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.36]) by fmsmga001.fm.intel.com with ESMTP; 21 Feb 2024 06:51:47 -0800 Date: Wed, 21 Feb 2024 23:05:27 +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 2/6] hw/display/macfb: Fix missing ERRP_GUARD() in macfb_nubus_realize() Message-ID: References: <20240221094317.994454-1-zhao1.liu@linux.intel.com> <20240221094317.994454-3-zhao1.liu@linux.intel.com> <874je2vyqs.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874je2vyqs.fsf@pond.sub.org> Received-SPF: none client-ip=192.198.163.15; 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 12:32:43PM +0100, Markus Armbruster wrote: > Date: Wed, 21 Feb 2024 12:32:43 +0100 > From: Markus Armbruster > Subject: Re: [PATCH 2/6] hw/display/macfb: Fix missing ERRP_GUARD() in > macfb_nubus_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 macfb_nubus_realize() - as a DeviceClass.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 > > macfb_nubus_realize(). > > > > Suggested-by: Markus Armbruster > > Signed-off-by: Zhao Liu > > --- > > Suggested by credit: > > Markus: Referred his explanation about ERRP_GUARD(). > > --- > > hw/display/macfb.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/hw/display/macfb.c b/hw/display/macfb.c > > index 418e99c8e18e..1ace341a0ff4 100644 > > --- a/hw/display/macfb.c > > +++ b/hw/display/macfb.c > > @@ -714,6 +714,7 @@ static void macfb_nubus_set_irq(void *opaque, int n, int level) > > > > static void macfb_nubus_realize(DeviceState *dev, Error **errp) > > { > > + ERRP_GUARD(); > > NubusDevice *nd = NUBUS_DEVICE(dev); > > MacfbNubusState *s = NUBUS_MACFB(dev); > > MacfbNubusDeviceClass *ndc = NUBUS_MACFB_GET_CLASS(dev); > > The dereference is > > ndc->parent_realize(dev, errp); > if (*errp) { > return; > } > > We check *errp, because neither the callback returns void. > > Reviewed-by: Markus Armbruster Thanks! Will add more description in commit message as you suggested. Regards, Zhao