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=-5.5 required=3.0 tests=BAYES_00, 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 93D16C433DF for ; Tue, 11 Aug 2020 11:15:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 792A320716 for ; Tue, 11 Aug 2020 11:15:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728664AbgHKLPz (ORCPT ); Tue, 11 Aug 2020 07:15:55 -0400 Received: from verein.lst.de ([213.95.11.211]:39919 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728469AbgHKLPy (ORCPT ); Tue, 11 Aug 2020 07:15:54 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 00C5C67357; Tue, 11 Aug 2020 13:15:51 +0200 (CEST) Date: Tue, 11 Aug 2020 13:15:51 +0200 From: Christoph Hellwig To: Miles Chen Cc: Christoph Hellwig , "David S . Miller" , linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com Subject: Re: [PATCH] net: untag pointer in sockptr_is_kernel Message-ID: <20200811111551.GA3958@lst.de> References: <20200811102704.17875-1-miles.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200811102704.17875-1-miles.chen@mediatek.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 11, 2020 at 06:27:04PM +0800, Miles Chen wrote: > From: Miles Chen > > sockptr_is_kernel() uses (sockptr.kernel >= TASK_SIZE) to tell > if the pointer is kernel space or user space. When user space uses > the "top byte ignored" feature such as HWAsan, we must untag > the pointer before checking against TASK_SIZE. > > sockptr_is_kernel() will view a tagged user pointer as a kernel pointer > and use memcpy directly and causes a kernel crash. Dave merged a patch from me to rever the optimized sockptr implementation for now. If we bring it back we should fold in your fix.