From owner-svn-src-stable-9@freebsd.org Sun Dec 18 14:31:12 2016 Return-Path: Delivered-To: svn-src-stable-9@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BBF9EC871A1; Sun, 18 Dec 2016 14:31:12 +0000 (UTC) (envelope-from dim@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 6B6AE1927; Sun, 18 Dec 2016 14:31:12 +0000 (UTC) (envelope-from dim@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id uBIEVBqi007829; Sun, 18 Dec 2016 14:31:11 GMT (envelope-from dim@FreeBSD.org) Received: (from dim@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id uBIEVBgn007828; Sun, 18 Dec 2016 14:31:11 GMT (envelope-from dim@FreeBSD.org) Message-Id: <201612181431.uBIEVBgn007828@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: dim set sender to dim@FreeBSD.org using -f From: Dimitry Andric Date: Sun, 18 Dec 2016 14:31:11 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r310228 - in stable: 10/sys/dev/xen/blkfront 11/sys/dev/xen/blkfront 9/sys/dev/xen/blkfront X-SVN-Group: stable-9 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-stable-9@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for only the 9-stable src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 18 Dec 2016 14:31:12 -0000 Author: dim Date: Sun Dec 18 14:31:11 2016 New Revision: 310228 URL: https://svnweb.freebsd.org/changeset/base/310228 Log: MFC r310013 (by cperciva): Check that blkfront devices have a non-zero number of sectors and a non-zero sector size. Such a device would be a virtual disk of zero bytes; clearly not useful, and not something we should try to attach. As a fortuitous side effect, checking that these values are non-zero here results in them not *becoming* zero later on the function. This odd behaviour began with r309124 (clang 3.9.0) but is challenging to debug; making any changes to this function whatsoever seems to affect the llvm optimizer behaviour enough to make the unexpected zeroing of the sector_size variable cease. PR: 215209 Security: The potential for variables to unexpectedly become zero has worrying consequences for security in general, but not so much in this particular context. MFC r310086: In xbd_connect(), use correct scanf conversion specifiers for the feature_barrier and feature_flush variables. Otherwise, adjacent variables on the stack, such as sector_size, may be overwritten, with disastrous results. Note that I did not see a good reason to revert the addition of zero checks introduced in r310013. Better safe than sorry. PR: 215209 Tested by: royger Modified: stable/9/sys/dev/xen/blkfront/blkfront.c Directory Properties: stable/9/ (props changed) stable/9/sys/ (props changed) Changes in other areas also in this revision: Modified: stable/10/sys/dev/xen/blkfront/blkfront.c stable/11/sys/dev/xen/blkfront/blkfront.c Directory Properties: stable/10/ (props changed) stable/11/ (props changed) Modified: stable/9/sys/dev/xen/blkfront/blkfront.c ============================================================================== --- stable/9/sys/dev/xen/blkfront/blkfront.c Sun Dec 18 14:10:24 2016 (r310227) +++ stable/9/sys/dev/xen/blkfront/blkfront.c Sun Dec 18 14:31:11 2016 (r310228) @@ -933,8 +933,16 @@ blkfront_connect(struct xb_softc *sc) xenbus_get_otherend_path(dev)); return; } + if ((sectors == 0) || (sector_size == 0)) { + xenbus_dev_fatal(dev, 0, + "invalid parameters from %s:" + " sectors = %lu, sector_size = %lu", + xenbus_get_otherend_path(dev), + sectors, sector_size); + return; + } err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev), - "feature-barrier", "%lu", &feature_barrier, + "feature-barrier", "%d", &feature_barrier, NULL); if (!err || feature_barrier) sc->xb_flags |= XB_BARRIER;