From patchwork Fri Mar 18 17:00:48 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Markus Armbruster X-Patchwork-Id: 8622211 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 43C23C0553 for ; Fri, 18 Mar 2016 17:06:01 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4F3082022A for ; Fri, 18 Mar 2016 17:06:00 +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 A0BED201BB for ; Fri, 18 Mar 2016 17:05:59 +0000 (UTC) Received: from localhost ([::1]:45056 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1agxqY-0006H8-Ld for patchwork-qemu-devel@patchwork.kernel.org; Fri, 18 Mar 2016 13:05:58 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41671) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1agxmI-0006Vb-9V for qemu-devel@nongnu.org; Fri, 18 Mar 2016 13:01:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1agxmE-00081l-2I for qemu-devel@nongnu.org; Fri, 18 Mar 2016 13:01:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49150) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1agxmD-00081V-U8 for qemu-devel@nongnu.org; Fri, 18 Mar 2016 13:01:30 -0400 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 77EE4C003592; Fri, 18 Mar 2016 17:01:29 +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 u2IH1RYI031573 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 18 Mar 2016 13:01:29 -0400 Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 5A1CC303F916; Fri, 18 Mar 2016 18:01:27 +0100 (CET) From: Markus Armbruster To: qemu-devel@nongnu.org Date: Fri, 18 Mar 2016 18:00:48 +0100 Message-Id: <1458320487-19603-2-git-send-email-armbru@redhat.com> In-Reply-To: <1458320487-19603-1-git-send-email-armbru@redhat.com> References: <1458320487-19603-1-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 Cc: Paolo Bonzini , Michael Roth Subject: [Qemu-devel] [PULL 01/40] 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 Message-Id: <1458066895-20632-2-git-send-email-armbru@redhat.com> Reviewed-by: Marc-André Lureau --- target-ppc/kvm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index 776336b..2fc9931 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;