From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1rcoMH-0004Nx-Bf for mharc-qemu-trivial@gnu.org; Wed, 21 Feb 2024 10:18:07 -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 1rcoKm-0000wD-Jc for qemu-trivial@nongnu.org; Wed, 21 Feb 2024 10:16:33 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rclA7-0000qW-4k for qemu-trivial@nongnu.org; Wed, 21 Feb 2024 06:53:22 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1708516398; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=WpWsv7TXPJRwiwzaQ7u0AhVyyYRTTjtj1qipgKCR3gg=; b=GyPvvhUG/UgT4BVmNSDjGdsD9X/opmQR3eJPkTPhqWnT1aoa+4KGjEBUjTabU8VaOByeyk uZBGxsSdiHeOgR7mcENsfptFv0aS3eMYXSmu+i0Ue5U1kAJ9GTOhoIAR5W+8hUg3FLx6wH 50MJikzxQRHCvcyPPSchTMkNnS22hbI= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-650-iSS_1aocPZGcr1kIRgCKQA-1; Wed, 21 Feb 2024 06:53:12 -0500 X-MC-Unique: iSS_1aocPZGcr1kIRgCKQA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F01503C0ED4E; Wed, 21 Feb 2024 11:53:11 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.55]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C5CAF8CE8; Wed, 21 Feb 2024 11:53:11 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id B82CB21E6740; Wed, 21 Feb 2024 12:53:10 +0100 (CET) From: Markus Armbruster To: Zhao Liu Cc: Jonathan Cameron , Fan Ni , Laurent Vivier , Alistair Francis , "Edgar E . Iglesias" , Peter Maydell , "Michael S . Tsirkin" , Marcel Apfelbaum , Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , 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() In-Reply-To: <20240221094317.994454-7-zhao1.liu@linux.intel.com> (Zhao Liu's message of "Wed, 21 Feb 2024 17:43:17 +0800") References: <20240221094317.994454-1-zhao1.liu@linux.intel.com> <20240221094317.994454-7-zhao1.liu@linux.intel.com> Date: Wed, 21 Feb 2024 12:53:10 +0100 Message-ID: <87h6i2uj89.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.05, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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=unavailable 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 15:16:35 -0000 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