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 2570CC433F5 for ; Mon, 25 Apr 2022 11:57:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236326AbiDYMA0 (ORCPT ); Mon, 25 Apr 2022 08:00:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236991AbiDYL7c (ORCPT ); Mon, 25 Apr 2022 07:59:32 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 078E56422 for ; Mon, 25 Apr 2022 04:56:28 -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 C8A04113E; Mon, 25 Apr 2022 04:56:22 -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 7120A3F73B; Mon, 25 Apr 2022 04:56:21 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, alex.popov@linux.com, catalin.marinas@arm.com, keescook@chromium.org, linux-arm-kernel@lists.infradead.org, luto@kernel.org, mark.rutland@arm.com, will@kernel.org Subject: [PATCH 6/8] stackleak: remove redundant check Date: Mon, 25 Apr 2022 12:56:01 +0100 Message-Id: <20220425115603.781311-7-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220425115603.781311-1-mark.rutland@arm.com> References: <20220425115603.781311-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In __stackleak_erase() we check that the `erase_low` value derived from `current->lowest_stack` is above the lowest legitimate stack pointer value, but this is already enforced by stackleak_track_stack() when recording the lowest stack value. Remove the redundant check. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Cc: Alexander Popov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Kees Cook --- kernel/stackleak.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/stackleak.c b/kernel/stackleak.c index f597d3323729d..ba346d46218f5 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -79,10 +79,6 @@ static __always_inline void __stackleak_erase(void) unsigned int poison_count = 0; const unsigned int depth = STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long); - /* Check that 'lowest_stack' value is sane */ - if (unlikely(erase_low - task_stack_low >= THREAD_SIZE)) - erase_low = task_stack_low; - /* Search for the poison value in the kernel stack */ while (erase_low > task_stack_low && poison_count <= depth) { if (*(unsigned long *)erase_low == STACKLEAK_POISON) -- 2.30.2