iwlwifi: check scan request ie_len

In mac80211 we always check both scan_req->ie and scan_req->ie_len
against zero before usage, in iwlwifi we should do the same.

Remove not needed "left -= ie_len" while at it.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-scan.c

@@ -644,10 +644,10 @@ u16 iwl_fill_probe_req(struct iwl_priv *priv, struct ieee80211_mgmt *frame,
 	if (WARN_ON(left < ie_len))
 		return len;
 
-	if (ies)
+	if (ies && ie_len) {
 		memcpy(pos, ies, ie_len);
-	len += ie_len;
-	left -= ie_len;
+		len += ie_len;
+	}
 
 	return (u16)len;
 }