From nobody Tue Apr 15 06:11:11 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (209.51.188.17 [209.51.188.17]) by mx.zohomail.com with SMTPS id 1549040572875611.5880863720711; Fri, 1 Feb 2019 09:02:52 -0800 (PST) Received: from localhost ([127.0.0.1]:58141 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gpcDE-0003LH-Gq for importer@patchew.org; Fri, 01 Feb 2019 12:02:44 -0500 Received: from eggs.gnu.org ([209.51.188.92]:39111) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gpbo5-0007nC-Q7 for qemu-devel@nongnu.org; Fri, 01 Feb 2019 11:36:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gpbo3-0008W9-Le for qemu-devel@nongnu.org; Fri, 01 Feb 2019 11:36:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37631) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gpbnt-000884-4F; Fri, 01 Feb 2019 11:36:33 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C4B1C796E0; Fri, 1 Feb 2019 16:35:50 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-117-95.ams2.redhat.com [10.36.117.95]) by smtp.corp.redhat.com (Postfix) with ESMTP id B2505608C8; Fri, 1 Feb 2019 16:35:49 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Date: Fri, 1 Feb 2019 17:35:04 +0100 Message-Id: <20190201163518.31157-14-kwolf@redhat.com> In-Reply-To: <20190201163518.31157-1-kwolf@redhat.com> References: <20190201163518.31157-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 01 Feb 2019 16:35:50 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 13/27] block/vpc: Don't take address of fields in packed structs X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" From: Peter Maydell Taking the address of a field in a packed struct is a bad idea, because it might not be actually aligned enough for that pointer type (and thus cause a crash on dereference on some host architectures). Newer versions of clang warn about this. Avoid the bug by generating the UUID into a local variable which is definitely safely aligned and then copying it into place. Signed-off-by: Peter Maydell Signed-off-by: Kevin Wolf --- block/vpc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/vpc.c b/block/vpc.c index d886465b7e..52ab717642 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -979,6 +979,7 @@ static int coroutine_fn vpc_co_create(BlockdevCreateOpt= ions *opts, int64_t total_size; int disk_type; int ret =3D -EIO; + QemuUUID uuid; =20 assert(opts->driver =3D=3D BLOCKDEV_DRIVER_VPC); vpc_opts =3D &opts->u.vpc; @@ -1062,7 +1063,8 @@ static int coroutine_fn vpc_co_create(BlockdevCreateO= ptions *opts, =20 footer->type =3D cpu_to_be32(disk_type); =20 - qemu_uuid_generate(&footer->uuid); + qemu_uuid_generate(&uuid); + footer->uuid =3D uuid; =20 footer->checksum =3D cpu_to_be32(vpc_checksum(buf, HEADER_SIZE)); =20 --=20 2.20.1