linux-kernel - [PATCH 3.10 32/56] vhost/scsi: potential memory corruption

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Message-Id: <20150929134701.802407277@linuxfoundation.org>
Date:	Tue, 29 Sep 2015 15:47:20 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
	Nicholas Bellinger <nab@...ux-iscsi.org>,
	Wang Long <long.wanglong@...wei.com>
Subject: [PATCH 3.10 32/56] vhost/scsi: potential memory corruption

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit 59c816c1f24df0204e01851431d3bab3eb76719c upstream.

This code in vhost_scsi_make_tpg() is confusing because we limit "tpgt"
to UINT_MAX but the data type of "tpg->tport_tpgt" and that is a u16.

I looked at the context and it turns out that in
vhost_scsi_set_endpoint(), "tpg->tport_tpgt" is used as an offset into
the vs_tpg[] array which has VHOST_SCSI_MAX_TARGET (256) elements so
anything higher than 255 then it is invalid.  I have made that the limit
now.

In vhost_scsi_send_evt() we mask away values higher than 255, but now
that the limit has changed, we don't need the mask.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
[ The affected function was renamed to vhost_scsi_make_tpg before
  the vulnerability was announced, I ported it to 3.10 stable and
  changed the code in function tcm_vhost_make_tpg]
Signed-off-by: Wang Long <long.wanglong@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/vhost/scsi.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1088,7 +1088,7 @@ static void tcm_vhost_send_evt(struct vh
 		 * lun[4-7] need to be zero according to virtio-scsi spec.
 		 */
 		evt->event.lun[0] = 0x01;
-		evt->event.lun[1] = tpg->tport_tpgt & 0xFF;
+		evt->event.lun[1] = tpg->tport_tpgt;
 		if (lun->unpacked_lun >= 256)
 			evt->event.lun[2] = lun->unpacked_lun >> 8 | 0x40 ;
 		evt->event.lun[3] = lun->unpacked_lun & 0xFF;
@@ -1894,12 +1894,12 @@ static struct se_portal_group *tcm_vhost
 			struct tcm_vhost_tport, tport_wwn);
 
 	struct tcm_vhost_tpg *tpg;
-	unsigned long tpgt;
+	u16 tpgt;
 	int ret;
 
 	if (strstr(name, "tpgt_") != name)
 		return ERR_PTR(-EINVAL);
-	if (kstrtoul(name + 5, 10, &tpgt) || tpgt > UINT_MAX)
+	if (kstrtou16(name + 5, 10, &tpgt) || tpgt >= VHOST_SCSI_MAX_TARGET)
 		return ERR_PTR(-EINVAL);
 
 	tpg = kzalloc(sizeof(struct tcm_vhost_tpg), GFP_KERNEL);


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