[PATCH AUTOSEL 5.4 008/187] mwifiex: fix possible heap overflow in mwifiex_process_country_ie()

[Sasha Levin <sashal@kernel.org>]

From: Ganapathi Bhat <gbhat@marvell.com>

[ Upstream commit 3d94a4a8373bf5f45cf5f939e88b8354dbf2311b ]

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 <huangwenabc@gmail.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/marvell/mwifiex/sta_ioctl.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/sta_ioctl.c b/drivers/net/wireless/marvell/mwifiex/sta_ioctl.c
index 74e50566db1f..6dd835f1efc2 100644
--- a/drivers/net/wireless/marvell/mwifiex/sta_ioctl.c
+++ b/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),
-- 
2.20.1