linux-kernel - [PATCH 3.10 039/139] libata: array underflow in ata_find

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1509571159-4405-40-git-send-email-w@1wt.eu>
Date:   Wed,  1 Nov 2017 22:17:39 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        Tejun Heo <tj@...nel.org>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 039/139] libata: array underflow in ata_find_dev()

From: Dan Carpenter <dan.carpenter@...cle.com>

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 <dan.carpenter@...cle.com>
Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: stable@...r.kernel.org 
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/ata/libata-scsi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index f3f0801..aa4e36b 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2794,10 +2794,12 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
 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];
 	}
 
-- 
2.8.0.rc2.1.gbe9624a