From mboxrd@z Thu Jan 1 00:00:00 1970 From: Harsh Bora Subject: Re: [PATCH] Typecasting required for comparing unlike datatypes Date: Fri, 10 Dec 2010 00:02:03 +0530 Message-ID: <4D0120A3.2040301@linux.vnet.ibm.com> References: <1291812900-18311-1-git-send-email-harsh@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Harsh Prateek Bora , linux-fsdevel@vger.kernel.org, fengguang.wu@intel.com, kamezawa.hiroyu@jp.fujitsu.com, aneesh.kumar@linux.vnet.ibm.com, jvrao@linux.vnet.ibm.com To: viro@ZenIV.linux.org.uk Return-path: Received: from e28smtp07.in.ibm.com ([122.248.162.7]:57643 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756832Ab0LIScK (ORCPT ); Thu, 9 Dec 2010 13:32:10 -0500 Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by e28smtp07.in.ibm.com (8.14.4/8.13.1) with ESMTP id oB9IW7JG007772 for ; Fri, 10 Dec 2010 00:02:07 +0530 Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id oB9IW74L4472990 for ; Fri, 10 Dec 2010 00:02:07 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id oB9IW5qa015904 for ; Fri, 10 Dec 2010 00:02:07 +0530 In-Reply-To: <1291812900-18311-1-git-send-email-harsh@linux.vnet.ibm.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hi Al, Any comments? On 12/08/2010 06:25 PM, Harsh Prateek Bora wrote: > The existing code causes the if condition to pass when it should fail > on a *64-bit kernel* because of implicit data type conversions. It can > be observed by passing pos = -1 and count = some positive number. > This results in function returning EOVERFLOW instead of EINVAL. > > With this patch, the function returns EINVAL when pos is -1 and count > is a positive number. This can be tested by calling sendfile with > offset = -1 and count = some positive number on a 64-bit kernel. > > Signed-off-by: Harsh Prateek Bora > --- > fs/read_write.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/fs/read_write.c b/fs/read_write.c > index 431a0ed..a8eabd4 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -38,7 +38,7 @@ __negative_fpos_check(struct file *file, loff_t pos, size_t count) > * pos or pos+count is negative here, check overflow. > * too big "count" will be caught in rw_verify_area(). > */ > - if ((pos< 0)&& (pos + count< pos)) > + if ((pos< 0)&& ( (loff_t) (pos + count)< pos)) > return -EOVERFLOW; > if (file->f_mode& FMODE_UNSIGNED_OFFSET) > return 0;