Staging: rtl8188eu: overflow in update_sta_support_rate()

The ->SupportedRates[] array has NDIS_802_11_LENGTH_RATES_EX (16)
elements.  Since "ie_len" comes from then network and can go up to 255
then it means we should add a range check to prevent memory corruption.

Fixes: d6846af6 ('staging: r8188eu: Add files for new driver - part 7')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/core/rtw_wlan_util.c

@@ -1599,13 +1599,18 @@ int update_sta_support_rate(struct adapter *padapter, u8 *pvar_ie, uint var_ie_l
 	pIE = (struct ndis_802_11_var_ie *)rtw_get_ie(pvar_ie, _SUPPORTEDRATES_IE_, &ie_len, var_ie_len);
 	if (pIE == NULL)
 		return _FAIL;
+	if (ie_len > NDIS_802_11_LENGTH_RATES_EX)
+		return _FAIL;
 
 	memcpy(pmlmeinfo->FW_sta_info[cam_idx].SupportedRates, pIE->data, ie_len);
 	supportRateNum = ie_len;
 
 	pIE = (struct ndis_802_11_var_ie *)rtw_get_ie(pvar_ie, _EXT_SUPPORTEDRATES_IE_, &ie_len, var_ie_len);
-	if (pIE)
+	if (pIE) {
+		if (supportRateNum + ie_len > NDIS_802_11_LENGTH_RATES_EX)
+			return _FAIL;
 		memcpy((pmlmeinfo->FW_sta_info[cam_idx].SupportedRates + supportRateNum), pIE->data, ie_len);
+	}
 
 	return _SUCCESS;
 }