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 19F32C47DDB for ; Tue, 23 Jan 2024 09:59:11 +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:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=0GZVwm3AAq3myuS6vI5hVweQoWP1l1t8YOqiKER3pWc=; b=RtFPO3YS05p1K5 p8guEvHZgiKkTSU4hB1OccVZTl+5z+MiT6WksavFppvYY8XKC3Xzuxno/GuCi08uGFs9P3N/P2j1T usTAdv/zO+1eVyi4uYZJnvp4aSIXJinRC4CkmjhSswtejDb4alutj/gqyPWWbwv6zd/hpk7fW/leL DOOJs4df3YECMTbR5ViTW6ly+gCSr0jO1ckNHoth30DRCs6f9wq+di+So5/BqvykN0/l6ci5FCjSh 5MFkfUiE905g93xVbRJdWJ8mgoJJ6JvF7s4qVA3TVjTFotGcSNnNYoAkeq3v3QcLq53auRsgDPnNH yWifKdrrvF7AxNkvi1Rw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rSDYL-00Fr8Y-0C; Tue, 23 Jan 2024 09:58:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rSDYH-00Fr7S-1W for linux-arm-kernel@lists.infradead.org; Tue, 23 Jan 2024 09:58:43 +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 7820A1FB; Tue, 23 Jan 2024 01:59:25 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.48.47]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E7C533F5A1; Tue, 23 Jan 2024 01:58:37 -0800 (PST) Date: Tue, 23 Jan 2024 09:58:35 +0000 From: Mark Rutland To: Kees Cook Cc: linux-hardening@vger.kernel.org, Catalin Marinas , Will Deacon , Kalesh Singh , Fuad Tabba , Mark Brown , "Madhavan T. Venkataraman" , Marc Zyngier , linux-arm-kernel@lists.infradead.org, "Gustavo A. R. Silva" , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org Subject: Re: [PATCH 40/82] arm64: stacktrace: Refactor intentional wrap-around test Message-ID: References: <20240122235208.work.748-kees@kernel.org> <20240123002814.1396804-40-keescook@chromium.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240123002814.1396804-40-keescook@chromium.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240123_015841_553357_5132CC97 X-CRM114-Status: GOOD ( 22.70 ) 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 On Mon, Jan 22, 2024 at 04:27:15PM -0800, Kees Cook wrote: > In an effort to separate intentional arithmetic wrap-around from > unexpected wrap-around, we need to refactor places that depend on this > kind of math. One of the most common code patterns of this is: > > VAR + value < VAR > > Notably, this is considered "undefined behavior" for signed and pointer > types, which the kernel works around by using the -fno-strict-overflow > option in the build[1] (which used to just be -fwrapv). Regardless, we > want to get the kernel source to the position where we can meaningfully > instrument arithmetic wrap-around conditions and catch them when they > are unexpected, regardless of whether they are signed[2], unsigned[3], > or pointer[4] types. > > Refactor open-coded wrap-around addition test to use add_would_overflow(). > This paves the way to enabling the wrap-around sanitizers in the future. > > Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] > Link: https://github.com/KSPP/linux/issues/26 [2] > Link: https://github.com/KSPP/linux/issues/27 [3] > Link: https://github.com/KSPP/linux/issues/344 [4] > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Kalesh Singh > Cc: Fuad Tabba > Cc: Mark Brown > Cc: "Madhavan T. Venkataraman" > Cc: Marc Zyngier > Cc: Mark Rutland > Cc: linux-arm-kernel@lists.infradead.org > Signed-off-by: Kees Cook > --- > arch/arm64/include/asm/stacktrace/common.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h > index f63dc654e545..6e0cb84961f8 100644 > --- a/arch/arm64/include/asm/stacktrace/common.h > +++ b/arch/arm64/include/asm/stacktrace/common.h > @@ -49,7 +49,7 @@ static inline bool stackinfo_on_stack(const struct stack_info *info, > if (!info->low) > return false; > > - if (sp < info->low || sp + size < sp || sp + size > info->high) > + if (sp < info->low || add_would_overflow(sp, size) || sp + size > info->high) > return false; This looks fine to me, so FWIW: Acked-by: Mark Rutland Mark. > > return true; > -- > 2.34.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel