[bug report] staging: ks7010: add driver from Nanonote extra-repository

[Dan Carpenter <error27@gmail.com>]

Hello Wolfram Sang,

The patch 13a9930d15b4: "staging: ks7010: add driver from Nanonote
extra-repository" from May 31, 2016, leads to the following Smatch
static checker warning:

	drivers/staging/ks7010/ks_wlan_net.c:2108 ks_wlan_set_wps_probe_req()
	error: 'len' from user is not capped properly

drivers/staging/ks7010/ks_wlan_net.c
    2088 static int ks_wlan_set_wps_probe_req(struct net_device *dev,
    2089                                      struct iw_request_info *info,
    2090                                      union iwreq_data *uwrq, char *extra)
    2091 {
    2092         struct iw_point *dwrq = &uwrq->data;
    2093         u8 *p = extra;
    2094         unsigned char len;
                 ^^^^^^^^^^^^^^^^^^

    2095         struct ks_wlan_private *priv = netdev_priv(dev);
    2096 
    2097         if (priv->sleep_mode == SLP_SLEEP)
    2098                 return -EPERM;
    2099 
    2100         /* length check */
    2101         if (p[1] + 2 != dwrq->length || dwrq->length > 256)

Should this be >= instead of >?  Otherwise if it's 256

    2102                 return -EINVAL;
    2103 
    2104         priv->wps.ielen = p[1] + 2 + 1;        /* IE header + IE + sizeof(len) */
    2105         len = p[1] + 2;        /* IE header + IE */

That means that "len" gets truncated to zero.

    2106 
    2107         memcpy(priv->wps.ie, &len, sizeof(len));
--> 2108         p = memcpy(priv->wps.ie + 1, p, len);
    2109 
    2110         netdev_dbg(dev, "%d(%#x): %02X %02X %02X %02X ... %02X %02X %02X\n",
    2111                    priv->wps.ielen, priv->wps.ielen, p[0], p[1], p[2], p[3],
    2112                    p[priv->wps.ielen - 3], p[priv->wps.ielen - 2],
    2113                    p[priv->wps.ielen - 1]);
    2114 
    2115         hostif_sme_enqueue(priv, SME_WPS_PROBE_REQUEST);
    2116 
    2117         return 0;
    2118 }

regards,
dan carpenter