From patchwork Wed Apr 8 14:52:08 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 459313 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 3A63814011D; Thu, 9 Apr 2015 00:52:19 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1YfrKx-0002km-GF; Wed, 08 Apr 2015 14:52:15 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1YfrKs-0002jg-9O for kernel-team@lists.ubuntu.com; Wed, 08 Apr 2015 14:52:10 +0000 Received: from av-217-129-142-138.netvisao.pt ([217.129.142.138] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1YfrKs-0003Rl-35 for kernel-team@lists.ubuntu.com; Wed, 08 Apr 2015 14:52:10 +0000 From: Luis Henriques To: kernel-team@lists.ubuntu.com Subject: [CVE-2015-2666][Utopic] x86/microcode/intel: Guard against stack overflow in the loader Date: Wed, 8 Apr 2015 15:52:08 +0100 Message-Id: <1428504728-22565-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com From: Quentin Casasnovas mc_saved_tmp is a static array allocated on the stack, we need to make sure mc_saved_count stays within its bounds, otherwise we're overflowing the stack in _save_mc(). A specially crafted microcode header could lead to a kernel crash or potentially kernel execution. Signed-off-by: Quentin Casasnovas Cc: "H. Peter Anvin" Cc: Fenghua Yu Link: http://lkml.kernel.org/r/1422964824-22056-1-git-send-email-quentin.casasnovas@oracle.com Signed-off-by: Borislav Petkov (cherry picked from commit f84598bd7c851f8b0bf8cd0d7c3be0d73c432ff4) BugLink: http://bugs.launchpad.net/bugs/1438504 CVE-2015-2666 Signed-off-by: Luis Henriques --- arch/x86/kernel/cpu/microcode/intel_early.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c index 18f739129e72..43a07bf48dea 100644 --- a/arch/x86/kernel/cpu/microcode/intel_early.c +++ b/arch/x86/kernel/cpu/microcode/intel_early.c @@ -321,7 +321,7 @@ get_matching_model_microcode(int cpu, unsigned long start, unsigned int mc_saved_count = mc_saved_data->mc_saved_count; int i; - while (leftover) { + while (leftover && mc_saved_count < ARRAY_SIZE(mc_saved_tmp)) { mc_header = (struct microcode_header_intel *)ucode_ptr; mc_size = get_totalsize(mc_header);