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From:   huangwenabc@gmail.com
To:     linux-wireless@vger.kernel.org
Subject: [PATCH] libertas: Fix two buffer overflows at parsing bss descriptor
Date:   Thu, 28 Nov 2019 18:51:04 +0800
Message-Id: <20191128105104.52920-1-huangwenabc@gmail.com>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

From: Wen Huang <huangwenabc@gmail.com>

add_ie_rates() copys rates without checking the length 
in bss descriptor from remote AP.when victim connects to 
remote attacker, this may trigger buffer overflow.
lbs_ibss_join_existing() copys rates without checking the length 
in bss descriptor from remote IBSS node.when victim connects to 
remote attacker, this may trigger buffer overflow.
Fix them by putting the length check before performing copy.

This fix addresses CVE-2019-14896 and CVE-2019-14897.
This also fix build warning of mixed declarations and code.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Wen Huang <huangwenabc@gmail.com>
---
 drivers/net/wireless/marvell/libertas/cfg.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/cfg.c b/drivers/net/wireless/marvell/libertas/cfg.c
index 57edfada0..c9401c121 100644
--- a/drivers/net/wireless/marvell/libertas/cfg.c
+++ b/drivers/net/wireless/marvell/libertas/cfg.c
@@ -273,6 +273,10 @@ add_ie_rates(u8 *tlv, const u8 *ie, int *nrates)
 	int hw, ap, ap_max = ie[1];
 	u8 hw_rate;
 
+	if (ap_max > MAX_RATES) {
+		lbs_deb_assoc("invalid rates\n");
+		return tlv;
+	}
 	/* Advance past IE header */
 	ie += 2;
 
@@ -1717,6 +1721,9 @@ static int lbs_ibss_join_existing(struct lbs_private *priv,
 	struct cmd_ds_802_11_ad_hoc_join cmd;
 	u8 preamble = RADIO_PREAMBLE_SHORT;
 	int ret = 0;
+	int hw, i;
+	u8 rates_max;
+	u8 *rates;
 
 	/* TODO: set preamble based on scan result */
 	ret = lbs_set_radio(priv, preamble, 1);
@@ -1775,9 +1782,12 @@ static int lbs_ibss_join_existing(struct lbs_private *priv,
 	if (!rates_eid) {
 		lbs_add_rates(cmd.bss.rates);
 	} else {
-		int hw, i;
-		u8 rates_max = rates_eid[1];
-		u8 *rates = cmd.bss.rates;
+		rates_max = rates_eid[1];
+		if (rates_max > MAX_RATES) {
+			lbs_deb_join("invalid rates");
+			goto out;
+		}
+		rates = cmd.bss.rates;
 		for (hw = 0; hw < ARRAY_SIZE(lbs_rates); hw++) {
 			u8 hw_rate = lbs_rates[hw].bitrate / 5;
 			for (i = 0; i < rates_max; i++) {
-- 
2.17.1