staging: r8188eu: memory corruption handling long ssids

We should cap the SSID length at NDIS_802_11_LENGTH_SSID (32) characters
to avoid memory corruption.  If the SSID is too long then I have opted
to ignore it instead of truncating it.

We don't need to clear bssid->Ssid.Ssid[0] because this struct is
allocated with rtw_zmalloc()
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NLarry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/core/rtw_wlan_util.c

@@ -912,12 +912,12 @@ int rtw_check_bcn_info(struct adapter  *Adapter, u8 *pframe, u32 packet_len)
 	unsigned char *pbuf;
 	u32 wpa_ielen = 0;
 	u8 *pbssid = GetAddr3Ptr(pframe);
-	u32 hidden_ssid = 0;
 	struct HT_info_element *pht_info = NULL;
 	struct rtw_ieee80211_ht_cap *pht_cap = NULL;
 	u32 bcn_channel;
 	unsigned short	ht_cap_info;
 	unsigned char	ht_info_infos_0;
+	int ssid_len;
 
 	if (is_client_associated_to_ap(Adapter) == false)
 		return true;
@@ -999,21 +999,15 @@ int rtw_check_bcn_info(struct adapter  *Adapter, u8 *pframe, u32 packet_len)
 	}
 
 	/* checking SSID */
+	ssid_len = 0;
 	p = rtw_get_ie(bssid->IEs + _FIXED_IE_LENGTH_, _SSID_IE_, &len, bssid->IELength - _FIXED_IE_LENGTH_);
-	if (p == NULL) {
-		DBG_88E("%s marc: cannot find SSID for survey event\n", __func__);
-		hidden_ssid = true;
-	} else {
-		hidden_ssid = false;
-	}
-
-	if ((NULL != p) && (false == hidden_ssid && (*(p + 1)))) {
-		memcpy(bssid->Ssid.Ssid, (p + 2), *(p + 1));
-		bssid->Ssid.SsidLength = *(p + 1);
-	} else {
-		bssid->Ssid.SsidLength = 0;
-		bssid->Ssid.Ssid[0] = '\0';
+	if (p) {
+		ssid_len = *(p + 1);
+		if (ssid_len > NDIS_802_11_LENGTH_SSID)
+			ssid_len = 0;
 	}
+	memcpy(bssid->Ssid.Ssid, (p + 2), ssid_len);
+	bssid->Ssid.SsidLength = ssid_len;
 
 	RT_TRACE(_module_rtl871x_mlme_c_, _drv_info_, ("%s bssid.Ssid.Ssid:%s bssid.Ssid.SsidLength:%d "
 				"cur_network->network.Ssid.Ssid:%s len:%d\n", __func__, bssid->Ssid.Ssid,