[PATCH 3.16.y-ckt 174/183] vhost/scsi: potential memory corruption

From: Luis Henriques
Date: Fri Mar 06 2015 - 05:03:30 EST


3.16.7-ckt8 -stable review patch. If anyone has any objections, please let me know.

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

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
[ luis: backported to 3.16: functions rename:
- tcm_vhost_send_evt -> vhost_scsi_send_evt
- tcm_vhost_make_tpg -> vhost_scsi_make_tpg ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
drivers/vhost/scsi.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index befe07b1e71d..0dfb3fd6e836 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1251,7 +1251,7 @@ tcm_vhost_send_evt(struct vhost_scsi *vs,
* 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;
@@ -2122,12 +2122,12 @@ tcm_vhost_make_tpg(struct se_wwn *wwn,
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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