From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1rcoa9-00062D-8g for mharc-qemu-trivial@gnu.org; Wed, 21 Feb 2024 10:32:26 -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 1rcoa5-0005fH-Tm; Wed, 21 Feb 2024 10:32:21 -0500 Received: from mgamail.intel.com ([198.175.65.19]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rco3f-0007g1-Dg; Wed, 21 Feb 2024 09:58:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1708527532; x=1740063532; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=XbDKq8C3hMQma9UmSzPUYiX8Eifflw1sLxBgBoa5q9E=; b=Syj4Q5KuYdnX6hz5RJFY75s0L8mMTBXSvmIHLKD/YDOdCpttmIi3kYG8 1MU//ZbdB6vI5IMPDYCCs7o5L2orFbFkd5ojENkx7zOiO6l8jjEf2BnCw XkV5gGFLd1ZItSIMAmQXYAnND6UfwAd6b8OZT4eyo2y4xnDUX/44knmXL 74xUBKAnvjI/aP6SRG9c0ZOcA4UqdlVPUfUCoV2xdH3EmdSDOepA0jjWV Nxr/llLjMOvjWZqAVgWHZp1e1bshJY8x3MSucuJxUuqf3cOehnUkIOuBR nOj3nFumflTBWUxkhkw/EhNKkLgd+1LQP+EnpJwbvakILVqntOicvHQg7 g==; X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="2552253" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="2552253" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Feb 2024 06:58:46 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="913319102" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="913319102" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.36]) by fmsmga002.fm.intel.com with ESMTP; 21 Feb 2024 06:58:42 -0800 Date: Wed, 21 Feb 2024 23:12:22 +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 6/6] hw/vfio/iommufd: Fix missing ERRP_GUARD() in iommufd_cdev_getfd() Message-ID: References: <20240221094317.994454-1-zhao1.liu@linux.intel.com> <20240221094317.994454-7-zhao1.liu@linux.intel.com> <87h6i2uj89.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87h6i2uj89.fsf@pond.sub.org> Received-SPF: none client-ip=198.175.65.19; 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 15:32:23 -0000 On Wed, Feb 21, 2024 at 12:53:10PM +0100, Markus Armbruster wrote: > Date: Wed, 21 Feb 2024 12:53:10 +0100 > From: Markus Armbruster > Subject: Re: [PATCH 6/6] hw/vfio/iommufd: Fix missing ERRP_GUARD() in > iommufd_cdev_getfd() > > 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 vfio_attach_device() - the caller of > > iommufd_cdev_getfd() - is always called in DeviceClass.realize() context > > and won't get the NULL errp parameter, iommufd_cdev_getfd() > > doesn't trigger the dereference issue. > > > > To follow the requirement of errp, add missing ERRP_GUARD() in > > iommufd_cdev_getfd(). > > > > Suggested-by: Markus Armbruster > > Signed-off-by: Zhao Liu > > --- > > Suggested by credit: > > Markus: Referred his explanation about ERRP_GUARD(). > > --- > > hw/vfio/iommufd.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c > > index 9bfddc136089..7baf49e6ee9e 100644 > > --- a/hw/vfio/iommufd.c > > +++ b/hw/vfio/iommufd.c > > @@ -116,6 +116,7 @@ static void iommufd_cdev_unbind_and_disconnect(VFIODevice *vbasedev) > > > > static int iommufd_cdev_getfd(const char *sysfs_path, Error **errp) > > { > > + ERRP_GUARD(); > > long int ret = -ENOTTY; > > char *path, *vfio_dev_path = NULL, *vfio_path = NULL; > > DIR *dir = NULL; > > The problematic use is > > if (*errp) { > error_prepend(errp, VFIO_MSG_PREFIX, path); > } > > Reviewed-by: Markus Armbruster > Thanks! Will also add the description of problematic use in commit message to make review easier. ;-) Regards, Zhao