From mboxrd@z Thu Jan 1 00:00:00 1970 From: Harsh Prateek Bora Subject: [PATCH] Typecasting required for comparing unlike datatypes Date: Wed, 8 Dec 2010 18:25:00 +0530 Message-ID: <1291812900-18311-1-git-send-email-harsh@linux.vnet.ibm.com> Cc: aneesh.kumar@linux.vnet.ibm.com, jvrao@linux.vnet.ibm.com, Harsh Prateek Bora To: linux-fsdevel@vger.kernel.org, fengguang.wu@intel.com, kamezawa.hiroyu@jp.fujitsu.com Return-path: Received: from e23smtp08.au.ibm.com ([202.81.31.141]:57344 "EHLO e23smtp08.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753544Ab0LHMzH (ORCPT ); Wed, 8 Dec 2010 07:55:07 -0500 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.31.245]) by e23smtp08.au.ibm.com (8.14.4/8.13.1) with ESMTP id oB8Ct5u7002470 for ; Wed, 8 Dec 2010 23:55:05 +1100 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id oB8Ct5GY667762 for ; Wed, 8 Dec 2010 23:55:05 +1100 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id oB8Ct4Tr001104 for ; Wed, 8 Dec 2010 23:55:05 +1100 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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; -- 1.7.1.1