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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 DFD36C3A5A6 for ; Thu, 29 Aug 2019 18:14:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C3C2123431 for ; Thu, 29 Aug 2019 18:14:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728919AbfH2SOn (ORCPT ); Thu, 29 Aug 2019 14:14:43 -0400 Received: from mga04.intel.com ([192.55.52.120]:3016 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728958AbfH2SOm (ORCPT ); Thu, 29 Aug 2019 14:14:42 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Aug 2019 11:14:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,444,1559545200"; d="scan'208";a="356532966" Received: from friedlmi-mobl1.ger.corp.intel.com (HELO localhost) ([10.252.54.26]) by orsmga005.jf.intel.com with ESMTP; 29 Aug 2019 11:14:40 -0700 Date: Thu, 29 Aug 2019 21:14:38 +0300 From: Jarkko Sakkinen To: Sean Christopherson Cc: linux-sgx@vger.kernel.org Subject: Re: [PATCH v2 2/5] x86/sgx: Reject concurrent ioctls on single enclave Message-ID: <20190829181438.oxix5d7qfgru7bd7@linux.intel.com> References: <20190827192717.27312-1-sean.j.christopherson@intel.com> <20190827192717.27312-3-sean.j.christopherson@intel.com> <20190829131543.ejdsviysr2u33rnj@linux.intel.com> <20190829160001.GD26580@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190829160001.GD26580@linux.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: NeoMutt/20180716 Sender: linux-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Thu, Aug 29, 2019 at 09:00:01AM -0700, Sean Christopherson wrote: > > #PF handler should be good as it has this conditional: > > > > flags = atomic_read(&encl->flags); > > > > if ((flags & SGX_ENCL_DEAD) || !(flags & SGX_ENCL_INITIALIZED)) > > return ERR_PTR(-EFAULT); > > > > What about the reclaimer? > > Can you elaborate? I'm not sure what you're asking. I'm thinking of a race between list_add() in the ioctl and list_move_tail() in the reclaimer. A quick way to fix this would be move sgx_alloc_va_page() from sgx_encl_grow() and return NULL if a new allocation is required. In the ioctl you can then allocate the page before taking locks and do "list_add(&va_page->list, &encl->va_pages);" behind the locks. /Jarkko