From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754820AbYJEMmp (ORCPT ); Sun, 5 Oct 2008 08:42:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753806AbYJEMmh (ORCPT ); Sun, 5 Oct 2008 08:42:37 -0400 Received: from rv-out-0506.google.com ([209.85.198.225]:21284 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753694AbYJEMmg (ORCPT ); Sun, 5 Oct 2008 08:42:36 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=L+o+qOjc//GUrcRxtl14xbUOsSkz+LjRjQQosXdLcEeA7FzcKMV81Wib8mL97rnUK5 ryLUY18YLZG6rv80q8PGpeMK1jCWkfGtts6X5N2sM0IRyvRMXNFKIrFTtQb6zewKU0Us hettUBB2ir4JoolI8zIl5ASXdnAqjdeVZ8QIA= Message-ID: <19f34abd0810050542k607221acs526b38aaba36b501@mail.gmail.com> Date: Sun, 5 Oct 2008 14:42:35 +0200 From: "Vegard Nossum" To: "Ingo Molnar" Subject: Re: kmemcheck: Caught 32-bit read from uninitialized memory (f6038ec0) Cc: "Pekka Enberg" , linux-kernel@vger.kernel.org In-Reply-To: <20080929131411.GA26442@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080928180652.GA8500@localhost.localdomain> <20080929085512.GA2190@elte.hu> <19f34abd0809290213m54a2c485p5917fcd46747ad6@mail.gmail.com> <20080929092546.GB7735@elte.hu> <20080929094308.GA18887@elte.hu> <20080929111314.GA28154@elte.hu> <20080929115757.GA3430@elte.hu> <20080929131411.GA26442@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 29, 2008 at 3:14 PM, Ingo Molnar wrote: > > another crash is below - config attached. > > Ingo > > -----------------> > initcall 0xc08eabf0 returned 0 after 7 msecs > calling 0xc08eae70 @ 1 > PnPBIOS: Scanning system for PnP BIOS support... > PnPBIOS: Found PnP BIOS installation structure at 0xc00fc550 > PnPBIOS: PnP BIOS version 1.0, entry 0xf0000:0xc580, dseg 0xf0000 > BUG: unable to handle kernel paging request at 0000c6ef Thanks, I can reproduce it. And that's very interesting. Look at the faulting address and the line just above: PnP BIOS version 1.0, entry 0xf0000:0xc580 When I run it, I get something similar: PnPBIOS: PnP BIOS version 1.0, entry 0xf0000:0x67ba, dseg 0xf0000 BUG: unable to handle kernel paging request at 000068ac Enabling debug information also gives me the location of the crash. It happens in kmemcheck's opcode decoder, when we dereference regs->eip. Is it possible that PnPBIOS is executing some code which is located at these weird addresses (like 16-bit code) and requires a different segment register? Maybe we should just check regs->flags to make sure that we are not in VM86 mode or similar. Will experiment a bit with it. Thanks. Vegard -- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036