From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932804AbbEZQMx (ORCPT ); Tue, 26 May 2015 12:12:53 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:33782 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753332AbbEZPmS (ORCPT ); Tue, 26 May 2015 11:42:18 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Quentin Casasnovas , "H. Peter Anvin" , Fenghua Yu , Borislav Petkov , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 02/92] x86/microcode/intel: Guard against stack overflow in the loader Date: Tue, 26 May 2015 08:40:06 -0700 Message-Id: <1432654896-28478-3-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1432654896-28478-1-git-send-email-kamal@canonical.com> References: <1432654896-28478-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Quentin Casasnovas commit f84598bd7c851f8b0bf8cd0d7c3be0d73c432ff4 upstream. 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 Reference: CVE-2015-2666 Signed-off-by: Kamal Mostafa --- 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 ec9df6f..5e109a3 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); -- 1.9.1