From nobody Sun Oct 26 07:37:42 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; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1521643391955191.55116381884807; Wed, 21 Mar 2018 07:43:11 -0700 (PDT) Received: from localhost ([::1]:55505 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eyexL-0008Ee-3j for importer@patchew.org; Wed, 21 Mar 2018 10:43:11 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37454) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eyevc-0006qK-UB for qemu-devel@nongnu.org; Wed, 21 Mar 2018 10:41:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eyeva-0002Cn-QI for qemu-devel@nongnu.org; Wed, 21 Mar 2018 10:41:24 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:34824 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eyeva-0002Ca-ME for qemu-devel@nongnu.org; Wed, 21 Mar 2018 10:41:22 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 33F2A83055DD; Wed, 21 Mar 2018 14:41:22 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-117-20.ams2.redhat.com [10.36.117.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id 84A9F215CDA7; Wed, 21 Mar 2018 14:41:21 +0000 (UTC) From: Kevin Wolf To: qemu-devel@nongnu.org Date: Wed, 21 Mar 2018 15:41:03 +0100 Message-Id: <20180321144107.22770-2-kwolf@redhat.com> In-Reply-To: <20180321144107.22770-1-kwolf@redhat.com> References: <20180321144107.22770-1-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 21 Mar 2018 14:41:22 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 21 Mar 2018 14:41:22 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'kwolf@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 1/5] multiboot: Reject kernels exceeding the address space 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: kwolf@redhat.com, peter.maydell@linaro.org 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" The code path where mh_load_end_addr is non-zero in the Multiboot header checks that mh_load_end_addr >=3D mh_load_addr and so mb_load_size is checked. However, mb_load_size is not checked when calculated from the file size, when mh_load_end_addr is 0. If the kernel binary size is larger than can fit in the address space after load_addr, we ended up with a kernel_size that is smaller than load_size, which means that we read the file into a too small buffer. Add a check to reject kernel files with such Multiboot headers. Signed-off-by: Kevin Wolf Reviewed-by: Jack Schwartz --- hw/i386/multiboot.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/i386/multiboot.c b/hw/i386/multiboot.c index b9064264d8..1e215bf8d3 100644 --- a/hw/i386/multiboot.c +++ b/hw/i386/multiboot.c @@ -247,6 +247,10 @@ int load_multiboot(FWCfgState *fw_cfg, } mb_load_size =3D kernel_file_size - mb_kernel_text_offset; } + if (mb_load_size > UINT32_MAX - mh_load_addr) { + error_report("kernel does not fit in address space"); + exit(1); + } if (mh_bss_end_addr) { if (mh_bss_end_addr < (mh_load_addr + mb_load_size)) { error_report("invalid bss_end_addr address"); --=20 2.13.6