From patchwork Tue Feb 9 11:37:52 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Markus Armbruster X-Patchwork-Id: 8260441 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E71549F38B for ; Tue, 9 Feb 2016 11:46:52 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4C90D2025A for ; Tue, 9 Feb 2016 11:46:52 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 88BA420114 for ; Tue, 9 Feb 2016 11:46:51 +0000 (UTC) Received: from localhost ([::1]:54639 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aT6kt-0006ZI-05 for patchwork-qemu-devel@patchwork.kernel.org; Tue, 09 Feb 2016 06:46:51 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34201) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aT6cW-0007rD-34 for qemu-devel@nongnu.org; Tue, 09 Feb 2016 06:38:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aT6cU-00030t-VD for qemu-devel@nongnu.org; Tue, 09 Feb 2016 06:38:11 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50556) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aT6cU-00030g-Ok for qemu-devel@nongnu.org; Tue, 09 Feb 2016 06:38:10 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id 65B908F296 for ; Tue, 9 Feb 2016 11:38:10 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-34.ams2.redhat.com [10.36.116.34]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u19Bc8SI025314 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 9 Feb 2016 06:38:09 -0500 Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 6BE233008AD1; Tue, 9 Feb 2016 12:38:04 +0100 (CET) From: Markus Armbruster To: qemu-devel@nongnu.org Date: Tue, 9 Feb 2016 12:37:52 +0100 Message-Id: <1455017883-25867-21-git-send-email-armbru@redhat.com> In-Reply-To: <1455017883-25867-1-git-send-email-armbru@redhat.com> References: <1455017883-25867-1-git-send-email-armbru@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 20/31] qapi: Don't cast Enum* to int* X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Blake C compilers are allowed to represent enums as a smaller type than int, if all enum values fit in the smaller type. There are even compiler flags that force the use of this smaller representation, although using them changes the ABI of a binary. Therefore, our generated code for visit_type_ENUM() (for all qapi enums) was wrong for casting Enum* to int* when calling visit_type_enum(). It appears that no one has been using compiler ABI switches for qemu, because if they had, we are potentially dereferencing beyond bounds or even risking a SIGBUS on platforms where unaligned pointer dereferencing is fatal. But it is still better to avoid the practice entirely, and just use the correct types. This matches the fix for alternate qapi types, done earlier in commit 0426d53 "qapi: Simplify visiting of alternate types", with generated code changing as: | void visit_type_QType(Visitor *v, QType *obj, const char *name, Error **errp) | { |- visit_type_enum(v, (int *)obj, QType_lookup, "QType", name, errp); |+ int value = *obj; |+ visit_type_enum(v, &value, QType_lookup, "QType", name, errp); |+ *obj = value; | } Signed-off-by: Eric Blake Reviewed-by: Marc-André Lureau Message-Id: <1454075341-13658-17-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster --- scripts/qapi-visit.py | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py index f98bb5f..ba75667 100644 --- a/scripts/qapi-visit.py +++ b/scripts/qapi-visit.py @@ -178,12 +178,13 @@ out: def gen_visit_enum(name): - # FIXME cast from enum *obj to int * invalidly assumes enum is int return mcgen(''' void visit_type_%(c_name)s(Visitor *v, %(c_name)s *obj, const char *name, Error **errp) { - visit_type_enum(v, (int *)obj, %(c_name)s_lookup, "%(name)s", name, errp); + int value = *obj; + visit_type_enum(v, &value, %(c_name)s_lookup, "%(name)s", name, errp); + *obj = value; } ''', c_name=c_name(name), name=name)