From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=HRiO=GX=lists.01.org=linux-nvdimm-bounces@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID,
	DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,
	SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 9D992C433DB
	for <linux-nvdimm@archiver.kernel.org>; Wed, 20 Jan 2021 20:37:42 +0000 (UTC)
Received: from ml01.01.org (ml01.01.org [198.145.21.10])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by mail.kernel.org (Postfix) with ESMTPS id 2B357233FC
	for <linux-nvdimm@archiver.kernel.org>; Wed, 20 Jan 2021 20:37:42 +0000 (UTC)
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B357233FC
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org
Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org
Received: from ml01.vlan13.01.org (localhost [IPv6:::1])
	by ml01.01.org (Postfix) with ESMTP id D94A0100EB337;
	Wed, 20 Jan 2021 12:37:41 -0800 (PST)
Received-SPF: None (mailfrom) identity=mailfrom; client-ip=2001:8b0:10b:1236::1; helo=casper.infradead.org; envelope-from=willy@infradead.org; receiver=<UNKNOWN> 
Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1])
	(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits))
	(No client certificate requested)
	by ml01.01.org (Postfix) with ESMTPS id 311E1100EB334
	for <linux-nvdimm@lists.01.org>; Wed, 20 Jan 2021 12:37:39 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed;
	d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version:
	References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:
	Content-Transfer-Encoding:Content-ID:Content-Description;
	bh=wha2ICxXtgWp8RSsmCA+ALoEMK4ppTh6Oifr+i/Aq5k=; b=POzz2vX4NL2FOL5KBbnP1afVXx
	7DUTchSw2uhr4v29pMLrprop/X/8ZeNKhQq7aAFkKjGCAaz+4r1ZagnvTwdmKGmT9i0FzNXsqZahm
	q9E7TLVeaTjgo4hB//QCK/z3qo/IC038TH8qoDfcTrbEX4HQwU+j3xjBQbd2dBZq1M8sL4f6Bgywx
	uWLIgA09gDv+4QyFtj2nzdZ6SX/r+mfucsyd3HnBXPOJQTMl8QIGIc+jM4N6BLZRg11soghFJAHDI
	MBF25b/+EoBQGmRDSRBoj1XqDhYK0b2JcmyiChLejE9AC5YkNQhOshX3nQckPpNNZoG+dbrcsXsTk
	Y0dgmP2g==;
Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux))
	id 1l2KC0-00GBPk-8o; Wed, 20 Jan 2021 20:35:07 +0000
Date: Wed, 20 Jan 2021 20:35:04 +0000
From: Matthew Wilcox <willy@infradead.org>
To: Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH v15 06/11] mm: introduce memfd_secret system call to
 create "secret" memory areas
Message-ID: <20210120203504.GM2260413@casper.infradead.org>
References: <20210120180612.1058-1-rppt@kernel.org>
 <20210120180612.1058-7-rppt@kernel.org>
MIME-Version: 1.0
Content-Disposition: inline
In-Reply-To: <20210120180612.1058-7-rppt@kernel.org>
Message-ID-Hash: SIUBC3IJA2LT7U4BQL2B66ZP37Y54DP6
X-Message-ID-Hash: SIUBC3IJA2LT7U4BQL2B66ZP37Y54DP6
X-MailFrom: willy@infradead.org
X-Mailman-Rule-Hits: nonmember-moderation
X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation
CC: Andrew Morton <akpm@linux-foundation.org>, Alexander Viro <viro@zeniv.linux.org.uk>, Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>, Catalin Marinas <catalin.marinas@arm.com>, Christopher Lameter <cl@linux.com>, Dave Hansen <dave.hansen@linux.intel.com>, David Hildenbrand <david@redhat.com>, Elena Reshetova <elena.reshetova@intel.com>, "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>, James Bottomley <jejb@linux.ibm.com>, "Kirill A. Shutemov" <kirill@shutemov.name>, Mark Rutland <mark.rutland@arm.com>, Mike Rapoport <rppt@linux.ibm.com>, Michael Kerrisk <mtk.manpages@gmail.com>, Palmer Dabbelt <palmer@dabbelt.com>, Paul Walmsley <paul.walmsley@sifive.com>, Peter Zijlstra <peterz@infradead.org>, Rick Edgecombe <rick.p.edgecombe@intel.com>, Roman Gushchin <guro@fb.com>, Shakeel Butt <shakeelb@google.com>, Shuah Khan <shuah@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Tycho Andersen <tycho@tycho.ws>, Will Deacon
  <will@kernel.org>, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, Hagen Paul Pfeifer <hagen@jauu.net>, Palmer Dabbelt <palmerdabbelt@google.com>
X-Mailman-Version: 3.1.1
Precedence: list
List-Id: "Linux-nvdimm developer list." <linux-nvdimm.lists.01.org>
Archived-At: <https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/SIUBC3IJA2LT7U4BQL2B66ZP37Y54DP6/>
List-Archive: <https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/>
List-Help: <mailto:linux-nvdimm-request@lists.01.org?subject=help>
List-Post: <mailto:linux-nvdimm@lists.01.org>
List-Subscribe: <mailto:linux-nvdimm-join@lists.01.org>
List-Unsubscribe: <mailto:linux-nvdimm-leave@lists.01.org>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit

On Wed, Jan 20, 2021 at 08:06:07PM +0200, Mike Rapoport wrote:
> +static struct page *secretmem_alloc_page(gfp_t gfp)
> +{
> +	/*
> +	 * FIXME: use a cache of large pages to reduce the direct map
> +	 * fragmentation
> +	 */
> +	return alloc_page(gfp);
> +}
> +
> +static vm_fault_t secretmem_fault(struct vm_fault *vmf)
> +{
> +	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
> +	struct inode *inode = file_inode(vmf->vma->vm_file);
> +	pgoff_t offset = vmf->pgoff;
> +	unsigned long addr;
> +	struct page *page;
> +	int err;
> +
> +	if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode))
> +		return vmf_error(-EINVAL);
> +
> +retry:
> +	page = find_lock_page(mapping, offset);
> +	if (!page) {
> +		page = secretmem_alloc_page(vmf->gfp_mask);
> +		if (!page)
> +			return VM_FAULT_OOM;
> +
> +		err = set_direct_map_invalid_noflush(page, 1);
> +		if (err)
> +			return vmf_error(err);

Haven't we leaked the page at this point?

> +		__SetPageUptodate(page);
> +		err = add_to_page_cache(page, mapping, offset, vmf->gfp_mask);

At this point, doesn't the page contain data from the last person to use
the page?  ie we've leaked data to this process?  I don't see anywhere
that we write data to the page.
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org