From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751207AbcELUIl (ORCPT ); Thu, 12 May 2016 16:08:41 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:49962 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750933AbcELUIj (ORCPT ); Thu, 12 May 2016 16:08:39 -0400 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: jejb@linux.vnet.ibm.com X-IBM-RcptTo: mroos@linux.ee;martin.petersen@oracle.com;hare@suse.com;linux-kernel@vger.kernel.org;linux-scsi@vger.kernel.org Message-ID: <1463083710.2380.46.camel@linux.vnet.ibm.com> Subject: Re: UBSAN: Undefined behaviour in drivers/scsi/aic7xxx/aic7xxx_core.c:2831:31 From: James Bottomley To: Meelis Roos , linux-scsi@vger.kernel.org, Linux Kernel list , Hannes Reinecke , "Martin K. Petersen" Date: Thu, 12 May 2016 13:08:30 -0700 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16051220-0005-0000-0000-00006CB01178 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2016-05-12 at 19:02 +0300, Meelis Roos wrote: > This is from a dual-AthlonMP 32-bit x86 system with onboard Adaptec > SCSI > controller, once during bootup. > > [ 4.896307] > ===================================================================== > =========== > [ 4.896471] UBSAN: Undefined behaviour in > drivers/scsi/aic7xxx/aic7xxx_core.c:2831:31 > [ 4.896629] shift exponent -1 is negative Is this some sort of false positive? The shift in question is devinfo->target_mask = (0x01 << devinfo->target_offset); The code which calls this in ahc_linux_initialize_scsi_bus() looks to be looping from 0-16 (or variations). Since the value passed in is unsigned, it would have to be set to ~0, which doesn't seem possible. James