From nobody Tue Oct 28 12:17:37 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1514484896579167.72580184786398; Thu, 28 Dec 2017 10:14:56 -0800 (PST) Received: from localhost ([::1]:60730 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eUchj-0004ux-IN for importer@patchew.org; Thu, 28 Dec 2017 13:14:55 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54711) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eUcbT-00086I-LP for qemu-devel@nongnu.org; Thu, 28 Dec 2017 13:08:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eUcbQ-00014U-WC for qemu-devel@nongnu.org; Thu, 28 Dec 2017 13:08:27 -0500 Received: from mav.lukeshu.com ([104.207.138.63]:58354) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eUcbQ-000105-Lq for qemu-devel@nongnu.org; Thu, 28 Dec 2017 13:08:24 -0500 Received: from build64-par (unknown [IPv6:2601:803:202:9275:da50:e6ff:fe00:4a5b]) by mav.lukeshu.com (Postfix) with ESMTPSA id BFD0280506; Thu, 28 Dec 2017 13:08:17 -0500 (EST) From: Luke Shumaker To: qemu-devel@nongnu.org Date: Thu, 28 Dec 2017 13:08:07 -0500 Message-Id: <20171228180814.9749-5-lukeshu@lukeshu.com> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171228180814.9749-1-lukeshu@lukeshu.com> References: <20171228180814.9749-1-lukeshu@lukeshu.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 104.207.138.63 Subject: [Qemu-devel] [PATCH 04/10] linux-user: init_guest_space: Correctly handle guest_start in commpage initialization X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Luke Shumaker , Riku Voipio , Laurent Vivier Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Luke Shumaker init_guest_commpage needs to check if the mapped space, which ends at real_start+real_size overlaps with where it needs to put the commpage, which is (assuming sane qemu_host_page_size) guest_base + 0xffff000, where guest_base is real_start - guest_start. [guest_base][ 0xffff0000 ][commpage] [guest_base][guest_start][real_size] [commpage] [ real_start ][real_size] [commpage] ^ fail if this gap < 0 Since init_guest_commpage wants to do everything relative to guest_base (rather than real_start), it obviously needs to be comparing 0xffff0000 against guest_start+real_size, not just real_size. This bug has been present since 806d102141b99d4f1e55a97d68b7ea8c8ba3129f in 2012, but guest_start is usually 0, and prior to v2.11 real_size was usually much smaller than 0xffff0000, so it was uncommon for it to have made a difference. Signed-off-by: Luke Shumaker Reviewed-by: Peter Maydell --- linux-user/elfload.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 1a6b660b25..f41cecc3cb 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1882,7 +1882,7 @@ unsigned long init_guest_space(unsigned long host_sta= rt, #if defined(TARGET_ARM) && !defined(TARGET_AARCH64) /* On 32-bit ARM, we need to also be able to map the commpage.= */ int valid =3D init_guest_commpage(real_start - guest_start, - real_size); + real_size + guest_start); if (valid =3D=3D 1) { break; } else if (valid =3D=3D -1) { --=20 2.15.1