From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751776AbbJQTW1 (ORCPT ); Sat, 17 Oct 2015 15:22:27 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:42723 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750950AbbJQTW0 (ORCPT ); Sat, 17 Oct 2015 15:22:26 -0400 Message-ID: <56229FEB.2040501@oracle.com> Date: Sat, 17 Oct 2015 15:22:19 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Al Viro , Andrey Ryabinin , willy@linux.intel.com CC: Chuck Ebbert , linux-fsdevel , LKML Subject: Re: fs: out of bounds on stack in iov_iter_advance References: <55CB5484.6080000@oracle.com> <20150815161338.4ea210ff@as> <55D1A6D4.3080605@gmail.com> <20150819054650.GD18890@ZenIV.linux.org.uk> <55FB75D0.7060403@oracle.com> <560C5469.5010704@oracle.com> In-Reply-To: <560C5469.5010704@oracle.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/30/2015 05:30 PM, Sasha Levin wrote: > On 09/17/2015 10:24 PM, Sasha Levin wrote: >> On 08/19/2015 01:46 AM, Al Viro wrote: >>>> or mapping->a_ops->direct_IO() returned more >>>>> than 'count'. >>> Was there DAX involved? ->direct_IO() in there is blkdev_direct_IO(), >>> which takes rather different paths in those cases... >>> >> >> So I've traced this all the way back to dax_io(). I can trigger this with: >> >> diff --git a/fs/dax.c b/fs/dax.c >> index 93bf2f9..2cdb8a5 100644 >> --- a/fs/dax.c >> +++ b/fs/dax.c >> @@ -178,6 +178,7 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, >> if (need_wmb) >> wmb_pmem(); >> >> + WARN_ON((pos == start) && (pos - start > iov_iter_count(iter))); >> return (pos == start) ? retval : pos - start; >> } >> >> So it seems that iter gets moved twice here: once in dax_io(), and once again >> back at generic_file_read_iter(). >> >> I don't see how it ever worked. Am I missing something? > > Ping? Ping? Thanks, Sasha