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=-12.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 13045C433E9 for ; Fri, 8 Jan 2021 15:38:35 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 9D09023888 for ; Fri, 8 Jan 2021 15:38:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D09023888 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.63648.112964 (Exim 4.92) (envelope-from ) id 1kxtqD-0005jM-4D; Fri, 08 Jan 2021 15:38:17 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 63648.112964; Fri, 08 Jan 2021 15:38:17 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kxtqD-0005jF-0o; Fri, 08 Jan 2021 15:38:17 +0000 Received: by outflank-mailman (input) for mailman id 63648; Fri, 08 Jan 2021 15:38:15 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kxtqB-0005jA-Af for xen-devel@lists.xenproject.org; Fri, 08 Jan 2021 15:38:15 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id efa5b7e6-0042-4512-bee6-15153a3ab0e6; Fri, 08 Jan 2021 15:38:14 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8105AAD89; Fri, 8 Jan 2021 15:38:13 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: efa5b7e6-0042-4512-bee6-15153a3ab0e6 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1610120293; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Nn6HPY4yJDUjBBIi4BmkXFmESHtgqGjNNQkl09oNOqc=; b=L5e2c2wuBNmVTaHZB5GIWKg/veHoe4x9vibQLm4ZR82oDgzAGvaEmgQIKXpE8QUF14xWVm vjNcltt+uwYv8ErvDGliWScqLiueamBcUTORXMk3O0wd/aLUr1G5oPz+n+EGyueclZtYIa ff6Jf/bEYBGnjNa+XkAHU6VaMYIYdcw= Subject: Re: [PATCH RFC 1/3] xen/hypfs: add support for bool leafs in dynamic directories To: Juergen Gross Cc: paul@xen.org, Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20201209161618.309-1-jgross@suse.com> <20201209161618.309-2-jgross@suse.com> From: Jan Beulich Message-ID: Date: Fri, 8 Jan 2021 16:38:13 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20201209161618.309-2-jgross@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 09.12.2020 17:16, Juergen Gross wrote: > --- a/xen/common/hypfs.c > +++ b/xen/common/hypfs.c > @@ -501,17 +501,26 @@ int hypfs_read_dir(const struct hypfs_entry *entry, > return 0; > } > > -int hypfs_read_leaf(const struct hypfs_entry *entry, > - XEN_GUEST_HANDLE_PARAM(void) uaddr) > +static int hypfs_read_leaf_off(const struct hypfs_entry *entry, > + XEN_GUEST_HANDLE_PARAM(void) uaddr, > + void *off) > { > const struct hypfs_entry_leaf *l; > unsigned int size = entry->funcs->getsize(entry); > + const void *ptr; > > ASSERT(this_cpu(hypfs_locked) != hypfs_unlocked); > > l = container_of(entry, const struct hypfs_entry_leaf, e); > + ptr = off ? off + (unsigned long)l->u.content : l->u.content; This is very irritating - you effectively add together two pointers. And even if this was correct for some reason, it would seem better readable as ptr = l->u.content + (unsigned long)off; to me. > --- a/xen/include/xen/hypfs.h > +++ b/xen/include/xen/hypfs.h > @@ -160,6 +160,8 @@ static inline void hypfs_string_set_reference(struct hypfs_entry_leaf *leaf, > HYPFS_FIXEDSIZE_INIT(var, XEN_HYPFS_TYPE_BOOL, nam, contvar, \ > &hypfs_bool_wr_funcs, 1) > > +#define HYPFS_STRUCT_ELEM(type, elem) (((type *)NULL)->elem) Kind of similar here - this very much looks like a NULL deref, avoidable by a user only if it takes the address of the construct. If there's really some non-pointer value to be encoded here, it would be better to avoid misuse by making the construct safe in a self-contained way. Jan