From patchwork Wed Jun 1 19:03:30 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laszlo Ersek X-Patchwork-Id: 69059 Delivered-To: patch@linaro.org Received: by 10.140.92.199 with SMTP id b65csp259480qge; Wed, 1 Jun 2016 12:03:41 -0700 (PDT) X-Received: by 10.98.102.205 with SMTP id s74mr11606304pfj.54.1464807821386; Wed, 01 Jun 2016 12:03:41 -0700 (PDT) Return-Path: Received: from ml01.01.org (ml01.01.org. [2001:19d0:306:5::1]) by mx.google.com with ESMTPS id g13si52673416pfg.160.2016.06.01.12.03.41 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 01 Jun 2016 12:03:41 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of edk2-devel-bounces@lists.01.org designates 2001:19d0:306:5::1 as permitted sender) client-ip=2001:19d0:306:5::1; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of edk2-devel-bounces@lists.01.org designates 2001:19d0:306:5::1 as permitted sender) smtp.mailfrom=edk2-devel-bounces@lists.01.org Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 76C271A1DF5; Wed, 1 Jun 2016 12:03:56 -0700 (PDT) X-Original-To: edk2-devel@ml01.01.org Delivered-To: edk2-devel@ml01.01.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 8BEC71A1DF5 for ; Wed, 1 Jun 2016 12:03:54 -0700 (PDT) Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9BFFE80500; Wed, 1 Jun 2016 19:03:38 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-116-149.phx2.redhat.com [10.3.116.149]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u51J3ZgK032052; Wed, 1 Jun 2016 15:03:37 -0400 From: Laszlo Ersek To: edk2-devel-01 Date: Wed, 1 Jun 2016 21:03:30 +0200 Message-Id: <1464807811-14917-2-git-send-email-lersek@redhat.com> In-Reply-To: <1464807811-14917-1-git-send-email-lersek@redhat.com> References: <1464807811-14917-1-git-send-email-lersek@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 01 Jun 2016 19:03:38 +0000 (UTC) Subject: [edk2] [PATCH 1/2] UefiCpuPkg: change PcdCpuSmmStackGuard default to TRUE X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Michael D Kinney , Jordan Justen , Jiewen Yao , Jeff Fan MIME-Version: 1.0 Errors-To: edk2-devel-bounces@lists.01.org Sender: "edk2-devel" This Feature PCD causes PiSmmCpuDxe to catch SMM stack overflow at runtime, logging a clear error message, and entering a CPU dead loop. Compared to the chaotic and catastrophic consequences of the stack leaking into, and corrupting, the SMM page table, a stack guard that is enabled by default is vastly superior. We should not require sane platforms to explicitly opt in to this safeguard; instead, we should require platforms that prefer to live dangerously to opt out of it. Stack overflow in SMM might even give rise to security vulnerabilities. Cc: Jeff Fan Cc: Jiewen Yao Cc: Jordan Justen Cc: Michael D Kinney Ref: http://thread.gmane.org/gmane.comp.bios.edk2.devel/12864 Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1341733 Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek --- UefiCpuPkg/UefiCpuPkg.dec | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 1.8.3.1 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec index 16637dfdc14b..ef46318a8935 100644 --- a/UefiCpuPkg/UefiCpuPkg.dec +++ b/UefiCpuPkg/UefiCpuPkg.dec @@ -85,11 +85,11 @@ [PcdsFeatureFlag] gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmBlockStartupThisAp|FALSE|BOOLEAN|0x32132108 ## Indicates if SMM Stack Guard will be enabled. - # If enabled, stack overflow in SMM can be caught which eases debugging.

+ # If enabled, stack overflow in SMM can be caught, preventing chaotic consequences.

# TRUE - SMM Stack Guard will be enabled.
# FALSE - SMM Stack Guard will be disabled.
# @Prompt Enable SMM Stack Guard. - gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackGuard|FALSE|BOOLEAN|0x1000001C + gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackGuard|TRUE|BOOLEAN|0x1000001C ## Indicates if BSP election in SMM will be enabled. # If enabled, a BSP will be dynamically elected among all processors in each SMI.