mwifiex: fix possible heap overflow in mwifiex_process_country_ie()

mwifiex_process_country_ie() function parse elements of bss
descriptor in beacon packet. When processing WLAN_EID_COUNTRY
element, there is no upper limit check for country_ie_len before
calling memcpy. The destination buffer domain_info->triplet is an
array of length MWIFIEX_MAX_TRIPLET_802_11D(83). The remote
attacker can build a fake AP with the same ssid as real AP, and
send malicous beacon packet with long WLAN_EID_COUNTRY elemen
(country_ie_len > 83). Attacker can  force STA connect to fake AP
on a different channel. When the victim STA connects to fake AP,
will trigger the heap buffer overflow. Fix this by checking for
length and if found invalid, don not connect to the AP.

This fix addresses CVE-2019-14895.

Reported-by: huangwen <[email protected]>
Signed-off-by: Ganapathi Bhat <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>

Author: gbhat-marvell

drivers/net/wireless/marvell/mwifiex/sta_ioctl.c

@@ -229,6 +229,14 @@ static int mwifiex_process_country_ie(struct mwifiex_private *priv,
 			    "11D: skip setting domain info in FW\n");
 		return 0;
 	}
+
+	if (country_ie_len >
+	    (IEEE80211_COUNTRY_STRING_LEN + MWIFIEX_MAX_TRIPLET_802_11D)) {
+		mwifiex_dbg(priv->adapter, ERROR,
+			    "11D: country_ie_len overflow!, deauth AP\n");
+		return -EINVAL;
+	}
+
 	memcpy(priv->adapter->country_code, &country_ie[2], 2);
 
 	domain_info->country_code[0] = country_ie[2];
@@ -272,8 +280,9 @@ int mwifiex_bss_start(struct mwifiex_private *priv, struct cfg80211_bss *bss,
 	priv->scan_block = false;
 
 	if (bss) {
-		if (adapter->region_code == 0x00)
-			mwifiex_process_country_ie(priv, bss);
+		if (adapter->region_code == 0x00 &&
+		    mwifiex_process_country_ie(priv, bss))
+			return -EINVAL;
 
 		/* Allocate and fill new bss descriptor */
 		bss_desc = kzalloc(sizeof(struct mwifiex_bssdescriptor),