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=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 DA344C43387 for ; Fri, 11 Jan 2019 13:59:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA12120872 for ; Fri, 11 Jan 2019 13:59:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jnkz4S8t" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732965AbfAKN7x (ORCPT ); Fri, 11 Jan 2019 08:59:53 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:51004 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725803AbfAKN7x (ORCPT ); Fri, 11 Jan 2019 08:59:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=vYokSj6HZdpVhgmsR5UYVRLNZuwSppMV4z0K7GJ9z1w=; b=jnkz4S8tu3lU+r+ywDhPiydWZQ aHhOxNg25NnKFYxGWR1KdwBx7azgolMUsJE65NnC7vrObpane5uygP7Upt/qaS0H6bpmIIZD1xzMA b1kVBHt9v0A/obRSuegJCyhoPTisCMP3WJUuCJ/BvThys6Lo8pmVCrysqd+JEy20R37mIn1Lv/e45 m2JLgN1hLt0bl2xGahQhHZOB749pfN87cTXb8s75DOo4dc3w4jdtsZUc0/Le+/WD5ieCeZKoOIkuV pxGM3/F6ftzofK0wPM55t6vQvXFftXYIzvTwn1mBTqHes7TXWGRqjLF9AHt3dnpMfS2JpBsOoixz5 MSa4e8GA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1ghxLi-0002mT-5f; Fri, 11 Jan 2019 13:59:50 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 56BB520194963; Fri, 11 Jan 2019 14:59:48 +0100 (CET) Date: Fri, 11 Jan 2019 14:59:48 +0100 From: Peter Zijlstra To: Esme Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , JJiri Olsa , Namhyung Kim , "linux-kernel@vger.kernel.org" Subject: Re: PROBLEM: syzkaller found / reduced C repro for non-fatal unchecked MSR access error Message-ID: <20190111135948.GA20688@hirez.programming.kicks-ass.net> References: <20190111100253.GO30894@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 11, 2019 at 01:37:50PM +0000, Esme wrote: > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Friday, January 11, 2019 5:02 AM, Peter Zijlstra wrote: > > > On Thu, Jan 10, 2019 at 11:21:16PM +0000, Esme wrote: > > > > > Attached is a fairly small C repro I did not see any references to > > > this possible flaw (unchecked MSR access) in relation to > > > __NR_perf_event_open > > > Attached is the config directly extracted from proc. This is the call > > > stack in relation to the MSR access error (5.0.0-rc1+), I get a very > > > similar stack running this test case on a stock Ubuntu > > > "4.18.0-11-generic" (pasted after this one). > > > > > -- Esme > > > [ 70.228744] unchecked MSR access error: WRMSR to 0xc0010000 (tried to write 0x0000020000130076) at rIP: 0xffffffff812dde28 (native_write_msr+0x8/0x30) > > > > That's K7_EVNTSEL0. What kind of hardware are you running this on? > > QEMU emulator version 3.0.93 (v3.1.0-rc3-dirty) > [ 0.000000] DMI: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 > > > [ 0.000000] Linux version 4.18.0-11-generic (buildd@lcy01-amd64-027) (gcc version 8.2.0 (Ubuntu 8.2.0-7ubuntu1)) #12-Ubuntu SMP Tue Oct 23 19:22:37 UTC 2018 (Ubuntu 4.18.0-11.12-generic 4.18.12) > [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.18.0-11-generic root=UUID=3a43ccb9-a433-4296-8dc5-0443f2a32128 ro quiet splash vt.handoff=1 > [ 0.000000] KERNEL supported cpus: > [ 0.000000] Intel GenuineIntel > [ 0.000000] AMD AuthenticAMD > [ 0.000000] Centaur CentaurHauls > [ 0.000000] random: get_random_u32 called from bsp_init_amd+0x205/0x2a0 with crng_init=0 > [ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers' > [ 0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers' > [ 0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers' > [ 0.000000] x86/fpu: xstate_offset[2]: 576, xstate_sizes[2]: 256 > [ 0.000000] x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'standard' format. Feh, then you get to figure out how the heck it passes check_hw_exists(). Stupid virt crap _again_.