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    Subject[PATCH 3.16.y-ckt 174/183] vhost/scsi: potential memory corruption
    Date
    3.16.7-ckt8 -stable review patch.  If anyone has any objections, please let me know.

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

    From: Dan Carpenter <dan.carpenter@oracle.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@oracle.com>
    Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
    [ 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@canonical.com>
    ---
    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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