From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S940778AbdEXP6J (ORCPT ); Wed, 24 May 2017 11:58:09 -0400 Received: from shelob.surriel.com ([96.67.55.147]:42251 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933797AbdEXP6D (ORCPT ); Wed, 24 May 2017 11:58:03 -0400 From: riel@redhat.com To: linux-kernel@vger.kernel.org Cc: danielmicay@gmail.com, tytso@mit.edu, keescook@chromium.org, hpa@zytor.com, luto@amacapital.net, mingo@kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, linux-sh@vger.kernel.org, ysato@users.sourceforge.jp, kernel-hardening@lists.openwall.com Subject: [PATCH 3/5] x86: ascii armor the x86_64 boot init stack canary Date: Wed, 24 May 2017 11:57:49 -0400 Message-Id: <20170524155751.424-4-riel@redhat.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20170524155751.424-1-riel@redhat.com> References: <20170524155751.424-1-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rik van Riel Use the ascii-armor canary to prevent unterminated C string overflows from being able to successfully overwrite the canary, even if they somehow obtain the canary value. Inspired by execshield ascii-armor and Daniel Micay's linux-hardened tree. Signed-off-by: Rik van Riel --- arch/x86/include/asm/stackprotector.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index dcbd9bcce714..8abedf1d650e 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -74,6 +74,7 @@ static __always_inline void boot_init_stack_canary(void) get_random_bytes(&canary, sizeof(canary)); tsc = rdtsc(); canary += tsc + (tsc << 32UL); + canary &= CANARY_MASK; current->stack_canary = canary; #ifdef CONFIG_X86_64 -- 2.9.3