From patchwork Fri Aug 16 16:00:26 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Williamson X-Patchwork-Id: 267699 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id C183A2C0288 for ; Sat, 17 Aug 2013 02:08:12 +1000 (EST) Received: from localhost ([::1]:59953 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VAMSy-00005H-QX for incoming@patchwork.ozlabs.org; Fri, 16 Aug 2013 12:01:32 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40664) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VAMS9-0008Jd-S6 for qemu-devel@nongnu.org; Fri, 16 Aug 2013 12:00:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VAMS3-0008TO-T0 for qemu-devel@nongnu.org; Fri, 16 Aug 2013 12:00:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48219) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VAMS3-0008T7-L8; Fri, 16 Aug 2013 12:00:35 -0400 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r7GG0VnM003311 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 16 Aug 2013 12:00:34 -0400 Received: from bling.home (ovpn-113-74.phx2.redhat.com [10.3.113.74]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r7GG0QvZ027591; Fri, 16 Aug 2013 12:00:27 -0400 To: qemu-devel@nongnu.org From: Alex Williamson Date: Fri, 16 Aug 2013 10:00:26 -0600 Message-ID: <20130816155430.16354.31104.stgit@bling.home> User-Agent: StGit/0.16 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: lersek@redhat.com, qemu-stable@nongnu.org, rth@twiddle.net Subject: [Qemu-devel] [PATCH v3] exec: Fix non-power-of-2 sized accesses 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Since commit 23326164 we align access sizes to match the alignment of the address, but we don't align the access size itself. This means we let illegal access sizes (ex. 3) slip through if the address is sufficiently aligned (ex. 4). This results in an abort which would be easy for a guest to trigger. Account for aligning the access size. Signed-off-by: Alex Williamson Cc: qemu-stable@nongnu.org --- v3: Highest power of 2, not lowest v2: Remove unnecessary loop condition exec.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/exec.c b/exec.c index 3ca9381..8c90cef 100644 --- a/exec.c +++ b/exec.c @@ -1924,6 +1924,13 @@ static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr) } } + /* Size must be a power of 2 */ + if (l & (l - 1)) { + while (!(l & access_size_max) && l & (access_size_max - 1)) { + access_size_max >>= 1; + } + } + /* Don't attempt accesses larger than the maximum. */ if (l > access_size_max) { l = access_size_max;