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 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 11C67C433EF for ; Mon, 25 Apr 2022 11:59:22 +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=Ifb3Kx9X3qM5FpTFoXvzFvsJPHaWw/mcv3Kn879aUU0=; b=ZZMmh6i98CC2DK D1cj3XEZkP0luNjfsrCNixUjy2XRdXeQoM6+R3PUhGLSfdEKcxmRpTdRWiDw61YjX89ufVB8A+KUf Z8djx1H7UpYY6ue/mXt5+4YMgn55sgN+Lsck66IgXO63VXYMn9ZR0pjVkl+da9THVdbWM7dsQZ7dX 0l0XqV2EpsUm+YmrmHn8czibkjbRcqk3MOmXdjp9pzeFUkmo4GaiEjFbew3dBkTAjXS6dByKHJg1A glG9AiTare2/3XljlZoa6gSOfqUT6PUzLGMlzPuU3Lx21stT+DMbQiSx9ERjoGD+LdH1Lf+iydTwV Ucmh12vqp+sPZsEqEa3w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nixMA-009OnD-D6; Mon, 25 Apr 2022 11:58:18 +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 1nixKO-009NsX-OT for linux-arm-kernel@lists.infradead.org; Mon, 25 Apr 2022 11:56:30 +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 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220425_045628_894959_DCD31F73 X-CRM114-Status: GOOD ( 11.44 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel