From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753484AbbEDMq0 (ORCPT ); Mon, 4 May 2015 08:46:26 -0400 Received: from ip4-83-240-67-251.cust.nbox.cz ([83.240.67.251]:51632 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753463AbbEDMqL (ORCPT ); Mon, 4 May 2015 08:46:11 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Quentin Casasnovas , "H. Peter Anvin" , Fenghua Yu , Borislav Petkov , Jiri Slaby Subject: [PATCH 3.12 115/155] x86/microcode/intel: Guard against stack overflow in the loader Date: Tue, 7 Apr 2015 14:51:24 +0200 Message-Id: <5ef12e01af366340f3cf91f8fb76242b415644d7.1428411004.git.jslaby@suse.cz> X-Mailer: git-send-email 2.3.4 In-Reply-To: <9a548862b8a26cbccc14f2c6c9c3688813d8d14b.1428411003.git.jslaby@suse.cz> References: <9a548862b8a26cbccc14f2c6c9c3688813d8d14b.1428411003.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Quentin Casasnovas 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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 Signed-off-by: Jiri Slaby --- arch/x86/kernel/microcode_intel_early.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/microcode_intel_early.c b/arch/x86/kernel/microcode_intel_early.c index 1575deb2e636..c44f7db7ce44 100644 --- a/arch/x86/kernel/microcode_intel_early.c +++ b/arch/x86/kernel/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); -- 2.3.4