From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932942AbcIAKdA (ORCPT ); Thu, 1 Sep 2016 06:33:00 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:42492 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932783AbcIAKc5 (ORCPT ); Thu, 1 Sep 2016 06:32:57 -0400 X-IBM-Helo: d06dlp03.portsmouth.uk.ibm.com X-IBM-MailFrom: heiko.carstens@de.ibm.com X-IBM-RcptTo: kernel-janitors@vger.kernel.org;linux-kernel@vger.kernel.org;linux-s390@vger.kernel.org Date: Thu, 1 Sep 2016 12:32:45 +0200 From: Heiko Carstens To: SF Markus Elfring Cc: linux-s390@vger.kernel.org, Martin Schwidefsky , Michael Holzheu , LKML , kernel-janitors@vger.kernel.org, Julia Lawall , Paolo Bonzini Subject: Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store() References: <5fd5f9ef-923f-4655-54f0-874114dc9428@users.sourceforge.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5fd5f9ef-923f-4655-54f0-874114dc9428@users.sourceforge.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16090110-0032-0000-0000-000002051BD4 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16090110-0033-0000-0000-00001C9E41B2 Message-Id: <20160901103245.GA3624@osiris> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-09-01_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1609010115 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote: > From: Markus Elfring > Date: Thu, 1 Sep 2016 11:30:58 +0200 > > A multiplication for the size determination of a memory allocation > indicated that an array data structure should be processed. > Thus use the corresponding function "kmalloc_array". > > This issue was detected by using the Coccinelle software. > > Signed-off-by: Markus Elfring > --- > arch/s390/hypfs/hypfs_diag0c.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c > index 0f1927c..61418a8 100644 > --- a/arch/s390/hypfs/hypfs_diag0c.c > +++ b/arch/s390/hypfs/hypfs_diag0c.c > @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count) > > get_online_cpus(); > cpu_count = num_online_cpus(); > - cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL); > + cpu_vec = kmalloc_array(num_possible_cpus(), > + sizeof(*cpu_vec), > + GFP_KERNEL); How does this improve the situation? For any real life scenario this can't overflow, but it does add an extra (pointless) runtime check, since num_possible_cpus() is not a compile time constant. So, why is this an "issue"?