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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 40752C73C7C for ; Wed, 10 Jul 2019 08:47:16 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 8F10C20838 for ; Wed, 10 Jul 2019 08:47:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F10C20838 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-16403-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 11426 invoked by uid 550); 10 Jul 2019 08:47:08 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 11394 invoked from network); 10 Jul 2019 08:47:08 -0000 Date: Wed, 10 Jul 2019 11:46:56 +0300 From: "Dmitry V. Levin" To: Xi Ruoyao Cc: Kees Cook , Jani Nikula , David Airlie , Jessica Yu , kernel-hardening@lists.openwall.com, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: kernel oops loading i915 after "x86/asm: Pin sensitive CR4 bits" (873d50d58) Message-ID: <20190710084656.GB5447@altlinux.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi, On Wed, Jul 10, 2019 at 01:44:17PM +0800, Xi Ruoyao wrote: > Hello, > > When I try to build and run the latest mainline kernel, it Oops loading i915 > module: > > BUG: unable to handle page fault for address: ffffffff9edc1598 > #PF: supervisor write access in kernel mode > #PF: error_code(0x0003) - permissions violation > PGD 1a20c067 P4D 1a20c067 PUD 1a20d063 PMD 8000000019e000e1 > Oops: 0003 [#1] SMP PTI > > The complete log is attached. > > Bisection tells "x86/asm: Pin sensitive CR4 bits" (873d50d58) is the first "bad" > commit. I can revert it and also "x86/asm: Pin sensitive CR0 bits" (8dbec27a2) > to make the kernel "seems to" work. > > I'm not a kernel expert so I can't tell if there is a bug in Kees' patch, or his > patch exploits a bug in i915 or module loader. This seems to be a kernel bug introduced after v5.2, see https://lore.kernel.org/lkml/CAHk-=wjh+h_-fd-gJz=wor42ZNmqq46QnB90jyfzqmKLsLFWOg@mail.gmail.com/ -- ldv