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 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 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 5CDDDC433DB for ; Wed, 20 Jan 2021 20:37:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C171D233FC for ; Wed, 20 Jan 2021 20:37:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C171D233FC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E930E6B0007; Wed, 20 Jan 2021 15:37:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E43CC6B0008; Wed, 20 Jan 2021 15:37:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D33696B000A; Wed, 20 Jan 2021 15:37:33 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id BCA466B0007 for ; Wed, 20 Jan 2021 15:37:33 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 8655B181AF5C2 for ; Wed, 20 Jan 2021 20:37:33 +0000 (UTC) X-FDA: 77727313986.30.test17_0209b682755d Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id 4FF65180B3C8B for ; Wed, 20 Jan 2021 20:37:33 +0000 (UTC) X-HE-Tag: test17_0209b682755d X-Filterd-Recvd-Size: 4297 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Wed, 20 Jan 2021 20:37:32 +0000 (UTC) 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 To: Mike Rapoport Cc: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , David Hildenbrand , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , 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 , Palmer Dabbelt 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-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210120180612.1058-7-rppt@kernel.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.