From nobody Sun May 5 19:07:14 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.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; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1584716765; cv=none; d=zohomail.com; s=zohoarc; b=kyTwxmxRx3d0Gvby+7PFjLlK6ASqHPBZyzKmrW6vqSGl1FYIpxfw3A3lNBAt9q8dbIXr27wWeTHCF30WjjFZW3ShnwczF6VPNz2Tc+2tyv/hNq+6SUq9dTe8g4pt9GWbuvpe9nnwK+fYcAWsRBqMC8LeHlRIC4Lq3OEREjw0LsE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1584716765; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:To; bh=2s+RuwgIkJMzwLNbUJw79v0XPHLUwu6+3Hl6Oz8WBpE=; b=TX/iLfOqoZBVXIrRRgOCSmLW0YKsG6bTn2kyAx1yMqvCTITZrkt9NZHIcyKu9wwoTqDh2WQtQ3VgQvzlcGiZ5ONTmghbZsu5sgSrBfQIbEOPiqX2RWo4qHTvnqNKJKMl7/XjxICQwiZFPeJvd8Ww3xXifA1rq7kldDBLpYFot6E= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1584716765990382.0188989970221; Fri, 20 Mar 2020 08:06:05 -0700 (PDT) Received: from localhost ([::1]:53932 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jFJDn-0004iA-VA for importer@patchew.org; Fri, 20 Mar 2020 11:06:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54891) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jFJD0-0004BZ-V3 for qemu-devel@nongnu.org; Fri, 20 Mar 2020 11:05:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jFJCz-0004ea-GZ for qemu-devel@nongnu.org; Fri, 20 Mar 2020 11:05:14 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:37864) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jFJCy-0004Vc-TD for qemu-devel@nongnu.org; Fri, 20 Mar 2020 11:05:13 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-387-qRvTKxH_PkSfiC-qSAZQmg-1; Fri, 20 Mar 2020 11:05:10 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 70195801E53; Fri, 20 Mar 2020 15:05:09 +0000 (UTC) Received: from blue.redhat.com (ovpn-112-193.phx2.redhat.com [10.3.112.193]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1D1DD19756; Fri, 20 Mar 2020 15:05:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584716712; 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: content-transfer-encoding:content-transfer-encoding; bh=2s+RuwgIkJMzwLNbUJw79v0XPHLUwu6+3Hl6Oz8WBpE=; b=DtWDpctZFRcTZK5iB4AhQgGOtsd9NI6xZGtuh4KJoxMk4H++e4XQ84vLhOHoBJrEkRPCLC pfHfmbEMHdFWCKa4m5IbaqmOmGrgaywrevG4PQUSXGlXYSeiTLmxE18ARAXS0yIhLPqN6t WXLF+bPVD9SWxTsfKIje3J9kVUtinqA= X-MC-Unique: qRvTKxH_PkSfiC-qSAZQmg-1 From: Eric Blake To: qemu-devel@nongnu.org Subject: [PATCH for-5.0] qga: Fix undefined C behavior Date: Fri, 20 Mar 2020 10:05:07 -0500 Message-Id: <20200320150507.994744-1-eblake@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 216.205.24.74 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Michael Roth Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) Content-Type: text/plain; charset="utf-8" The QAPI struct GuestFileWhence has a comment about how we are exploiting equivalent values between two different integer types shared in a union. But C says behavior is undefined on assignments to overlapping storage when the two types are not the same width, and indeed, 'int64_t value' and 'enum QGASeek name' are very likely to be different in width. Utilize a temporary variable to fix things. Reported-by: Peter Maydell Fixes: 0b4b49387 Fixes: Coverity CID 1421990 Signed-off-by: Eric Blake --- qga/commands.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/qga/commands.c b/qga/commands.c index f8852beb9ca4..4471a9f08d38 100644 --- a/qga/commands.c +++ b/qga/commands.c @@ -482,10 +482,15 @@ done: * the guest's SEEK_ constants. */ int ga_parse_whence(GuestFileWhence *whence, Error **errp) { - /* Exploit the fact that we picked values to match QGA_SEEK_*. */ + /* + * Exploit the fact that we picked values to match QGA_SEEK_*; + * however, we have to use a temporary variable since the union + * members may have different size. + */ if (whence->type =3D=3D QTYPE_QSTRING) { + int value =3D whence->u.name; whence->type =3D QTYPE_QNUM; - whence->u.value =3D whence->u.name; + whence->u.value =3D value; } switch (whence->u.value) { case QGA_SEEK_SET: --=20 2.25.1