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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 7E237C2BB48 for ; Thu, 17 Dec 2020 11:28:52 +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 2B72823441 for ; Thu, 17 Dec 2020 11:28:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B72823441 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.55871.97463 (Exim 4.92) (envelope-from ) id 1kprSR-0003EU-QC; Thu, 17 Dec 2020 11:28:31 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 55871.97463; Thu, 17 Dec 2020 11:28:31 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kprSR-0003EN-MH; Thu, 17 Dec 2020 11:28:31 +0000 Received: by outflank-mailman (input) for mailman id 55871; Thu, 17 Dec 2020 11:28:29 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kprSP-0003EI-R7 for xen-devel@lists.xenproject.org; Thu, 17 Dec 2020 11:28:29 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 5b58acd1-4d25-4eab-9f96-c6f2c4fb68cf; Thu, 17 Dec 2020 11:28:29 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 53BD1AC7B; Thu, 17 Dec 2020 11:28:28 +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: 5b58acd1-4d25-4eab-9f96-c6f2c4fb68cf 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=1608204508; 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=byGWWpcSVKqbTQcQ3wglN0nxKpOX6GFjlcWDjhuWRCA=; b=BMHSblRqwWT0JsPaZVrZ2j9yy9Hx0qq2aeixNTEDjjapT64dHfmakiSrqsKS3stIC0wsQP 7xOAnXfF5JSwEXlJt3Ps64zSudxtCE8JDoOGcLwPNvXLMupYvyZ/cW8V9MnGX79WMc1n6a 59MzIOcbm6vqZEKFV6RWem122261rU8= Subject: Re: [PATCH v3 5/8] xen/hypfs: add support for id-based dynamic directories To: Juergen Gross Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20201209160956.32456-1-jgross@suse.com> <20201209160956.32456-6-jgross@suse.com> From: Jan Beulich Message-ID: <2894a231-9150-7c09-cc5c-7ef52087acf5@suse.com> Date: Thu, 17 Dec 2020 12:28:28 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: <20201209160956.32456-6-jgross@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 09.12.2020 17:09, Juergen Gross wrote: > +static const struct hypfs_entry *hypfs_dyndir_enter( > + const struct hypfs_entry *entry) > +{ > + const struct hypfs_dyndir_id *data; > + > + data = hypfs_get_dyndata(); > + > + /* Use template with original enter function. */ > + return data->template->e.funcs->enter(&data->template->e); > +} At the example of this (applies to other uses as well): I realize hypfs_get_dyndata() asserts that the pointer is non-NULL, but according to the bottom of ./CODING_STYLE this may not be enough when considering the implications of a NULL deref in the context of a PV guest. Even this living behind a sysctl doesn't really help, both because via XSM not fully privileged domains can be granted access, and because speculation may still occur all the way into here. (I'll send a patch to address the latter aspect in a few minutes.) While likely we have numerous existing examples with similar problems, I guess in new code we'd better be as defensive as possible. > +/* > + * Fill dyndata with a dynamically generated directory based on a template > + * and a numerical id. > + * Needs to be kept in sync with hypfs_read_dyndir_id_entry() regarding the > + * name generated. > + */ > +struct hypfs_entry *hypfs_gen_dyndir_id_entry( > + const struct hypfs_entry_dir *template, unsigned int id, void *data) > +{ s/directory/entry/ in the comment (and as a I realize only now then also for hypfs_read_dyndir_id_entry())? Jan