From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFD55C433F5 for ; Wed, 27 Apr 2022 17:32:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244395AbiD0Rf7 (ORCPT ); Wed, 27 Apr 2022 13:35:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244363AbiD0RfW (ORCPT ); Wed, 27 Apr 2022 13:35:22 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D9D312360C5 for ; Wed, 27 Apr 2022 10:31:55 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C1BA9143D; Wed, 27 Apr 2022 10:31:55 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8DA463F73B; Wed, 27 Apr 2022 10:31:54 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: akpm@linux-foundation.org, alex.popov@linux.com, catalin.marinas@arm.com, keescook@chromium.org, linux-kernel@vger.kernel.org, luto@kernel.org, mark.rutland@arm.com, will@kernel.org Subject: [PATCH v2 11/13] lkdtm/stackleak: check stack boundaries Date: Wed, 27 Apr 2022 18:31:26 +0100 Message-Id: <20220427173128.2603085-12-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220427173128.2603085-1-mark.rutland@arm.com> References: <20220427173128.2603085-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The stackleak code relies upon the current SP and lowest recorded SP falling within expected task stack boundaries. Check this at the start of the test. Signed-off-by: Mark Rutland Cc: Alexander Popov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Catalin Marinas Cc: Kees Cook Cc: Will Deacon --- drivers/misc/lkdtm/stackleak.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/misc/lkdtm/stackleak.c b/drivers/misc/lkdtm/stackleak.c index 46c60761a05ea..52800583fd051 100644 --- a/drivers/misc/lkdtm/stackleak.c +++ b/drivers/misc/lkdtm/stackleak.c @@ -35,6 +35,25 @@ static void noinstr check_stackleak_irqoff(void) unsigned long poison_high, poison_low; bool test_failed = false; + /* + * Check that the current and lowest recorded stack pointer values fall + * within the expected task stack boundaries. These tests should never + * fail unless the boundaries are incorrect or we're clobbering the + * STACK_END_MAGIC, and in either casee something is seriously wrong. + */ + if (current_sp < task_stack_low || current_sp >= task_stack_high) { + pr_err("FAIL: current_stack_pointer (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n", + current_sp, task_stack_low, task_stack_high - 1); + test_failed = true; + goto out; + } + if (lowest_sp < task_stack_low || lowest_sp >= task_stack_high) { + pr_err("FAIL: current->lowest_stack (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n", + lowest_sp, task_stack_low, task_stack_high - 1); + test_failed = true; + goto out; + } + /* * Depending on what has run prior to this test, the lowest recorded * stack pointer could be above or below the current stack pointer. @@ -87,6 +106,7 @@ static void noinstr check_stackleak_irqoff(void) poison_high - task_stack_low, task_stack_low - task_stack_base); +out: if (test_failed) { pr_err("FAIL: the thread stack is NOT properly erased!\n"); pr_expected_config(CONFIG_GCC_PLUGIN_STACKLEAK); -- 2.30.2