vhost/scsi: potential memory corruption

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@oracle.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index daf10b7fa311..ab4811f749f5 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1249,7 +1249,7 @@ vhost_scsi_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;
@@ -2120,12 +2120,12 @@ vhost_scsi_make_tpg(struct se_wwn *wwn,
                         struct vhost_scsi_tport, tport_wwn);
 
         struct vhost_scsi_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 vhost_scsi_tpg), GFP_KERNEL);