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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 06EC6C3A5A3 for ; Fri, 30 Aug 2019 04:30:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CCC1222CE9 for ; Fri, 30 Aug 2019 04:30:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726090AbfH3EaD (ORCPT ); Fri, 30 Aug 2019 00:30:03 -0400 Received: from mail105.syd.optusnet.com.au ([211.29.132.249]:34419 "EHLO mail105.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725812AbfH3EaD (ORCPT ); Fri, 30 Aug 2019 00:30:03 -0400 Received: from dread.disaster.area (pa49-181-255-194.pa.nsw.optusnet.com.au [49.181.255.194]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 95475360EAD; Fri, 30 Aug 2019 14:30:00 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92) (envelope-from ) id 1i3YXu-0003RX-IX; Fri, 30 Aug 2019 14:29:58 +1000 Date: Fri, 30 Aug 2019 14:29:58 +1000 From: Dave Chinner To: Kees Cook Cc: Jason Yan , kernel-hardening@lists.openwall.com, linux-fsdevel@vger.kernel.org Subject: Re: CONFIG_HARDENED_USERCOPY Message-ID: <20190830042958.GC7777@dread.disaster.area> References: <6e02a518-fea9-19fe-dca7-0323a576750d@huawei.com> <201908290914.F0F929EA@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201908290914.F0F929EA@keescook> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=FNpr/6gs c=1 sm=1 tr=0 a=YO9NNpcXwc8z/SaoS+iAiA==:117 a=YO9NNpcXwc8z/SaoS+iAiA==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=FmdZ9Uzk2mMA:10 a=7-415B0cAAAA:8 a=hzK9nwXln0vweuEjbcYA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Aug 29, 2019 at 09:15:36AM -0700, Kees Cook wrote: > On Thu, Aug 29, 2019 at 08:42:30PM +0800, Jason Yan wrote: > > We found an issue of kernel bug related to HARDENED_USERCOPY. > > When copying an IO buffer to userspace, HARDENED_USERCOPY thought it is > > illegal to copy this buffer. Actually this is because this IO buffer was > > merged from two bio vectors, and the two bio vectors buffer was allocated > > with kmalloc() in the filesystem layer. > > Ew. I thought the FS layer was always using page_alloc? No, they don't. It's perfectly legal to use heap memory for bio buffers - we've been doing it since, at least, XFS got merged all those years ago. Cheers, Dave. -- Dave Chinner david@fromorbit.com