From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: UBSAN: Undefined behaviour in block/blk-mq.c:1459:27 with pata_amd Date: Mon, 16 May 2016 09:55:31 -0600 Message-ID: <5739ED73.4020009@kernel.dk> References: <22191628.vH7YQZ1hRO@amdc1976> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ig0-f172.google.com ([209.85.213.172]:36861 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752202AbcEPPze (ORCPT ); Mon, 16 May 2016 11:55:34 -0400 Received: by mail-ig0-f172.google.com with SMTP id qe5so52230886igc.1 for ; Mon, 16 May 2016 08:55:34 -0700 (PDT) In-Reply-To: <22191628.vH7YQZ1hRO@amdc1976> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Bartlomiej Zolnierkiewicz , Meelis Roos Cc: Linux Kernel list , linux-ide@vger.kernel.org, linux-block@vger.kernel.org, Tejun Heo On 05/13/2016 09:31 AM, Bartlomiej Zolnierkiewicz wrote: > Does the patch below help? > > From: Bartlomiej Zolnierkiewicz > Subject: [PATCH] blk-mq: fix undefined behaviour in order_to_size() > > When this_order variable in blk_mq_init_rq_map() becomes zero > the code incorrectly decrements the variable and passes the result > to order_to_size() helper causing undefined behaviour: > > UBSAN: Undefined behaviour in block/blk-mq.c:1459:27 > shift exponent 4294967295 is too large for 32-bit type 'unsigned int' > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc6-00072-g33656a1 #22 > > Fix the code by checking this_order variable for not having the zero > value first. Thanks Bart, added for 4.7. -- Jens Axboe