From patchwork Mon Feb 15 15:27:39 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 382964 Delivered-To: patch@linaro.org Received: by 2002:a02:c80e:0:0:0:0:0 with SMTP id p14csp1175124jao; Mon, 15 Feb 2021 07:43:27 -0800 (PST) X-Google-Smtp-Source: ABdhPJz4gj4ShV2K71B1/F6/VUROrqus8AemNLITwukmNyIpXlpQF52kt31D3byk+l5La4WmDQZn X-Received: by 2002:a17:906:3ac3:: with SMTP id z3mr15968836ejd.449.1613403807310; Mon, 15 Feb 2021 07:43:27 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1613403807; cv=none; d=google.com; s=arc-20160816; b=vE7dzxEdrmHtCShfDTOr4sbJSU7Eo7kwy3ASB/ogJBZ27sGDpsJvb5CzpoHnw5uNYK dxOZwd8WtZMRSJfbeLdzRiLMpBYgGx2WlZcga+J80FPYx6Ja1k8sTmuaCResnkf9ieVW 5uxfNNsr52NJntfhAt4ZejMYlwsG38LHITUi/QQ2UQjj/cpqWMp1ZQkcOog700XUnvKu cInMK6GleQjWLBSDWVMWbQLf+TqaUDJqoxlPH0/82hlbmwPkIEzaR/zvEdszoUS9fEj8 gzrAxGc7SLfOf2uUAT6vOx3S0JPkc6VkCczwq8c0meF6EC/JGanSentBwqBCiaYyyswe IgPw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=2hr7broQn5T70dJ33IUByW6lCw3Sr8r/y6gKvNPDWgI=; b=Bt8TrZD3i1HlMAI3LXIg4bE0earl4WlPrzo+XGptWtpJnmHymfNWOTIjzT1pTp8Cfz 0+4l3MT6bgNTb5xgZlJr8rqeDP7UG870QhxezWb0pU3Xspqf16RmdpoviK0siWWGgHg7 vRCYo76KJNobS5UMwP4Np+jI+t//gYKkgoyT9DtauDLijlKupbzytknb5ZgUtdvc1qm5 cYZjZkQi4WBOaNkBiNR3nIU0X/zZ5fFd3i2AUSnOcFzafWFB/DFOd1NrU21y+0YECe5Q j+xoi/cSSvV8Os8Vnvwzy4k0VWGROgnth1doJQngdTPb7MOw52QnKCVVf3v7GIVZjGgI Ed6g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="O9OWi/Y/"; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id b7si12442700ejz.39.2021.02.15.07.43.26; Mon, 15 Feb 2021 07:43:27 -0800 (PST) Received-SPF: pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="O9OWi/Y/"; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231444AbhBOPmL (ORCPT + 13 others); Mon, 15 Feb 2021 10:42:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:50184 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230517AbhBOPiI (ORCPT ); Mon, 15 Feb 2021 10:38:08 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 01EC564EF0; Mon, 15 Feb 2021 15:34:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1613403252; bh=PhHRtP7GNe8NZYZl0FnzuQgNhTym4Yt74x7V66+22CE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O9OWi/Y/Ce/ZdgWNtg++pg5jtY6yv5Z1cNJPKfsztL9NE/40urAk+NUPQgL6YDQyO kFZIYbpw6F0VA9fbLhs7H/+7QJ/m26ZUCfk2HOmUTWriD+tqV1RpwAoowGs7kLMV8+ 3li8NbSlD96RR4rhBFiORWoMoaeR8/kQvVqOvm8w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Catalin Marinas , Will Deacon , Luis Machado , Vincenzo Frascino Subject: [PATCH 5.10 086/104] arm64: mte: Allow PTRACE_PEEKMTETAGS access to the zero page Date: Mon, 15 Feb 2021 16:27:39 +0100 Message-Id: <20210215152722.229588462@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210215152719.459796636@linuxfoundation.org> References: <20210215152719.459796636@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Catalin Marinas commit 68d54ceeec0e5fee4fb8048e6a04c193f32525ca upstream. The ptrace(PTRACE_PEEKMTETAGS) implementation checks whether the user page has valid tags (mapped with PROT_MTE) by testing the PG_mte_tagged page flag. If this bit is cleared, ptrace(PTRACE_PEEKMTETAGS) returns -EIO. A newly created (PROT_MTE) mapping points to the zero page which had its tags zeroed during cpu_enable_mte(). If there were no prior writes to this mapping, ptrace(PTRACE_PEEKMTETAGS) fails with -EIO since the zero page does not have the PG_mte_tagged flag set. Set PG_mte_tagged on the zero page when its tags are cleared during boot. In addition, to avoid ptrace(PTRACE_PEEKMTETAGS) succeeding on !PROT_MTE mappings pointing to the zero page, change the __access_remote_tags() check to (vm_flags & VM_MTE) instead of PG_mte_tagged. Signed-off-by: Catalin Marinas Fixes: 34bfeea4a9e9 ("arm64: mte: Clear the tags when a page is mapped in user-space with PROT_MTE") Cc: # 5.10.x Cc: Will Deacon Reported-by: Luis Machado Tested-by: Luis Machado Reviewed-by: Vincenzo Frascino Link: https://lore.kernel.org/r/20210210180316.23654-1-catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/cpufeature.c | 6 +----- arch/arm64/kernel/mte.c | 3 ++- 2 files changed, 3 insertions(+), 6 deletions(-) --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1696,16 +1696,12 @@ static void bti_enable(const struct arm6 #ifdef CONFIG_ARM64_MTE static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap) { - static bool cleared_zero_page = false; - /* * Clear the tags in the zero page. This needs to be done via the * linear map which has the Tagged attribute. */ - if (!cleared_zero_page) { - cleared_zero_page = true; + if (!test_and_set_bit(PG_mte_tagged, &ZERO_PAGE(0)->flags)) mte_clear_page_tags(lm_alias(empty_zero_page)); - } } #endif /* CONFIG_ARM64_MTE */ --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -239,11 +239,12 @@ static int __access_remote_tags(struct m * would cause the existing tags to be cleared if the page * was never mapped with PROT_MTE. */ - if (!test_bit(PG_mte_tagged, &page->flags)) { + if (!(vma->vm_flags & VM_MTE)) { ret = -EOPNOTSUPP; put_page(page); break; } + WARN_ON_ONCE(!test_bit(PG_mte_tagged, &page->flags)); /* limit access to the end of the page */ offset = offset_in_page(addr);