Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752207AbdHISi2 (ORCPT ); Wed, 9 Aug 2017 14:38:28 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56744 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750740AbdHISOb (ORCPT ); Wed, 9 Aug 2017 14:14:31 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Carpenter , Tejun Heo Subject: [PATCH 4.9 04/93] libata: array underflow in ata_find_dev() Date: Wed, 9 Aug 2017 11:12:57 -0700 Message-Id: <20170809181335.833720390@linuxfoundation.org> X-Mailer: git-send-email 2.14.0 In-Reply-To: <20170809181335.658857427@linuxfoundation.org> References: <20170809181335.658857427@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1498 Lines: 44 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Carpenter commit 59a5e266c3f5c1567508888dd61a45b86daed0fa upstream. My static checker complains that "devno" can be negative, meaning that we read before the start of the loop. I've looked at the code, and I think the warning is right. This come from /proc so it's root only or it would be quite a quite a serious bug. The call tree looks like this: proc_scsi_write() <- gets id and channel from simple_strtoul() -> scsi_add_single_device() <- calls shost->transportt->user_scan() -> ata_scsi_user_scan() -> ata_find_dev() Signed-off-by: Dan Carpenter Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- drivers/ata/libata-scsi.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -2971,10 +2971,12 @@ static unsigned int atapi_xlat(struct at static struct ata_device *ata_find_dev(struct ata_port *ap, int devno) { if (!sata_pmp_attached(ap)) { - if (likely(devno < ata_link_max_devices(&ap->link))) + if (likely(devno >= 0 && + devno < ata_link_max_devices(&ap->link))) return &ap->link.device[devno]; } else { - if (likely(devno < ap->nr_pmp_links)) + if (likely(devno >= 0 && + devno < ap->nr_pmp_links)) return &ap->pmp_link[devno].device[0]; }