From patchwork Wed Apr 27 17:31:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 12829284 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B2CC3C433F5 for ; Wed, 27 Apr 2022 17:39:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=W63RWm6NWoSRsNuoO8B/OewOOXH1YcC+XtILJcaQHVw=; b=CEaQ13NY0JRqoj UYwdcXNQ0GPH77nRCZnJ7qUqOAsfbPXbn3Q8w0yfrml4L7nh9fIZe3+JKEGlxCdwCMu72FmNSfZX8 M/zbnuvOoTjL8rpfDP9OeRc2hYgDHkN9usdazBRBEeiMT43uhzjLohGu4AB4hTHfbHHfQC4WsONVp JJ85p3TuAsHffJCDig2s7NId5V2Vf8AC14OEOnbCTdxJ+BWWl7xpcZ2it/SmOdlXOg4S0nOcO9YvF v3iXH71Nh+a6Jc1+1Q/UqLaKr1uIL47zgSZr9KzI8hughysYsPzQF1Do58wghZO1W0T9NAO9KE7MN SHPj1d+zMDVhhU9fzHNA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1njlci-002iyE-Ic; Wed, 27 Apr 2022 17:38:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1njlVu-002gWV-GK for linux-arm-kernel@lists.infradead.org; Wed, 27 Apr 2022 17:31:44 +0000 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 0D2001477; Wed, 27 Apr 2022 10:31:41 -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 C48B73F73B; Wed, 27 Apr 2022 10:31:39 -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 03/13] stackleak: remove redundant check Date: Wed, 27 Apr 2022 18:31:18 +0100 Message-Id: <20220427173128.2603085-4-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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220427_103142_691577_F54B55E1 X-CRM114-Status: GOOD ( 11.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 753eab797a04d..f7a0f8cf73c37 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -78,10 +78,6 @@ 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(kstack_ptr - boundary >= THREAD_SIZE)) - kstack_ptr = boundary; - /* Search for the poison value in the kernel stack */ while (kstack_ptr > boundary && poison_count <= depth) { if (*(unsigned long *)kstack_ptr == STACKLEAK_POISON)