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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 4666DC4363A for ; Mon, 5 Oct 2020 14:12:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1046B205F4 for ; Mon, 5 Oct 2020 14:12:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="WCeoFFDb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726143AbgJEOM5 (ORCPT ); Mon, 5 Oct 2020 10:12:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725932AbgJEOM5 (ORCPT ); Mon, 5 Oct 2020 10:12:57 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71C14C0613CE for ; Mon, 5 Oct 2020 07:12:57 -0700 (PDT) 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=5TuOPBNUbBRAJMMBLTJFw8fxPCEcRsnpEHgAKrQ+zrU=; b=WCeoFFDbWsaAOe8YZ0TJ8uP91A Od4sJtYXCyZDrm4tQe9JsF2ATuA+SQjk0HXn3oozQJ3MpM2clrw+vqqUf+DAI8YA/CJo9GxDppsFe Zvp6rWeduvyBWAyAXK1u6ubiXCgghSi3j5qgekEecgMzsNj4mgv6L7PIiTd0J8kpyqYY0tQHBwN34 /oFaQ9zxFGcxfhlzN7Z7k+Qxz1ZTpqV2yRv9G0kUq+/VbieEcy3yCfxyKWQ9euP8aIVDEBBFp+V+Z KIoXUtkOZPNXKRoVWL3+3yhkjK/6zmiSeprqBo4g9voOpDp/mt82XG0zu7v2asPc3q+ALqX4RSpZx 2ZQYKrIA==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kPREU-00050m-KV; Mon, 05 Oct 2020 14:12:54 +0000 Date: Mon, 5 Oct 2020 15:12:54 +0100 From: Matthew Wilcox To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org, Haitao Huang , Sean Christopherson , Jethro Beekman , Dave Hansen Subject: Re: [PATCH v3] x86/sgx: Fix sgx_encl_may_map locking Message-ID: <20201005141254.GL20115@casper.infradead.org> References: <20201005141119.5395-1-jarkko.sakkinen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201005141119.5395-1-jarkko.sakkinen@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Mon, Oct 05, 2020 at 05:11:19PM +0300, Jarkko Sakkinen wrote: > Fix the issue further discussed in: No, this is still utter crap. Just use the version I sent. > 1. https://lore.kernel.org/linux-sgx/op.0rwbv916wjvjmi@mqcpg7oapc828.gar.corp.intel.com/ > 2. https://lore.kernel.org/linux-sgx/20201003195440.GD20115@casper.infradead.org/ > > Reported-by: Haitao Huang > Suggested-by: Matthew Wilcox > Cc: Sean Christopherson > Cc: Jethro Beekman > Cc: Dave Hansen > Signed-off-by: Jarkko Sakkinen > --- > v3: > * Added the missing unlock pointed out by Matthew. > * Tested with the correct patch (last time had v1 applied) > * I don't know what happened to v2 changelog, checked from patchwork > and it wasn't there. Hope this is not scraped. > arch/x86/kernel/cpu/sgx/encl.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c > index 4c6407cd857a..e91e521b03a8 100644 > --- a/arch/x86/kernel/cpu/sgx/encl.c > +++ b/arch/x86/kernel/cpu/sgx/encl.c > @@ -307,6 +307,8 @@ int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start, > unsigned long idx_start = PFN_DOWN(start); > unsigned long idx_end = PFN_DOWN(end - 1); > struct sgx_encl_page *page; > + unsigned long count = 0; > + int ret = 0; > > XA_STATE(xas, &encl->page_array, idx_start); > > @@ -317,11 +319,30 @@ int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start, > if (current->personality & READ_IMPLIES_EXEC) > return -EACCES; > > - xas_for_each(&xas, page, idx_end) > - if (!page || (~page->vm_max_prot_bits & vm_prot_bits)) > - return -EACCES; > + /* > + * No need to hold encl->lock: > + * 1. None of the page->* get written. > + * 2. page->vm_max_prot_bits is set in sgx_encl_page_alloc(). This > + * is before calling xa_insert(). After that it is never modified. > + */ > + xas_lock(&xas); > + xas_for_each(&xas, page, idx_end) { > + if (++count % XA_CHECK_SCHED) > + continue; > > - return 0; > + if (!page || (~page->vm_max_prot_bits & vm_prot_bits)) { > + ret = -EACCES; > + break; > + } > + > + xas_pause(&xas); > + xas_unlock(&xas); > + cond_resched(); > + xas_lock(&xas); > + } > + xas_unlock(&xas); > + > + return ret; > } > > static int sgx_vma_mprotect(struct vm_area_struct *vma, > -- > 2.25.1 >