From patchwork Mon Mar 7 19:25:15 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Markus Armbruster X-Patchwork-Id: 8521771 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 A7D339F8A8 for ; Mon, 7 Mar 2016 19:28:22 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1DE13202C8 for ; Mon, 7 Mar 2016 19:28:22 +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 7235C20295 for ; Mon, 7 Mar 2016 19:28:21 +0000 (UTC) Received: from localhost ([::1]:57904 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ad0pI-0007xI-PO for patchwork-qemu-devel@patchwork.kernel.org; Mon, 07 Mar 2016 14:28:20 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44520) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ad0n4-0003zc-DT for qemu-devel@nongnu.org; Mon, 07 Mar 2016 14:26:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ad0n1-0003sH-G4 for qemu-devel@nongnu.org; Mon, 07 Mar 2016 14:26:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39237) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ad0n1-0003sA-An for qemu-devel@nongnu.org; Mon, 07 Mar 2016 14:25:59 -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 E25BFC00B8D4; Mon, 7 Mar 2016 19:25:57 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-61.ams2.redhat.com [10.36.116.61]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u27JPtR3005209 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 7 Mar 2016 14:25:57 -0500 Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3836830010E7; Mon, 7 Mar 2016 20:25:55 +0100 (CET) From: Markus Armbruster To: qemu-devel@nongnu.org Date: Mon, 7 Mar 2016 20:25:15 +0100 Message-Id: <1457378754-21649-4-git-send-email-armbru@redhat.com> In-Reply-To: <1457378754-21649-1-git-send-email-armbru@redhat.com> References: <1457378754-21649-1-git-send-email-armbru@redhat.com> 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 Cc: claudio.fontana@huawei.com, Michael Roth , david.marchand@6wind.com, mlureau@redhat.com, pbonzini@redhat.com, cam@cs.ualberta.ca Subject: [Qemu-devel] [PATCH v2 03/42] target-ppc: Document TOCTTOU in hugepage support 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 The code to find the minimum page size is is vulnerable to TOCTTOU. Added in commit 2d103aa "target-ppc: fix hugepage support when using memory-backend-file" (v2.4.0). Since I can't fix it myself right now, add a FIXME comment. Cc: Paolo Bonzini Cc: Michael Roth Signed-off-by: Markus Armbruster --- target-ppc/kvm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index d67c169..0ef6ecd 100644 --- a/target-ppc/kvm.c +++ b/target-ppc/kvm.c @@ -333,6 +333,12 @@ static long gethugepagesize(const char *mem_path) return fs.f_bsize; } +/* + * FIXME TOCTTOU: this iterates over memory backends' mem-path, which + * may or may not name the same files / on the same filesystem now as + * when we actually open and map them. Iterate over the file + * descriptors instead, and use qemu_fd_getpagesize(). + */ static int find_max_supported_pagesize(Object *obj, void *opaque) { char *mem_path;