[PATCH] mwifiex: Fix possible buffer overflows in mwifiex_cmd_802_11_ad_hoc_start

[Tim Gardner]

From: Zhang Xiaohui <ruc_zhangxiaohui at 163.com>

CVE-CVE-2020-36158

mwifiex_cmd_802_11_ad_hoc_start() calls memcpy() without checking
the destination size may trigger a buffer overflower,
which a local user could use to cause denial of service
or the execution of arbitrary code.
Fix it by putting the length check before calling memcpy().

Signed-off-by: Zhang Xiaohui <ruc_zhangxiaohui at 163.com>
Signed-off-by: Kalle Valo <kvalo at codeaurora.org>
Link: https://lore.kernel.org/r/20201206084801.26479-1-ruc_zhangxiaohui@163.com
(cherry picked from commit 5c455c5ab332773464d02ba17015acdca198f03d)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 drivers/net/wireless/marvell/mwifiex/join.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/marvell/mwifiex/join.c b/drivers/net/wireless/marvell/mwifiex/join.c
index d87aeff70cef..c2cb1e711c06 100644
--- a/drivers/net/wireless/marvell/mwifiex/join.c
+++ b/drivers/net/wireless/marvell/mwifiex/join.c
@@ -877,6 +877,8 @@ mwifiex_cmd_802_11_ad_hoc_start(struct mwifiex_private *priv,
 
 	memset(adhoc_start->ssid, 0, IEEE80211_MAX_SSID_LEN);
 
+	if (req_ssid->ssid_len > IEEE80211_MAX_SSID_LEN)
+		req_ssid->ssid_len = IEEE80211_MAX_SSID_LEN;
 	memcpy(adhoc_start->ssid, req_ssid->ssid, req_ssid->ssid_len);
 
 	mwifiex_dbg(adapter, INFO, "info: ADHOC_S_CMD: SSID = %s\n",
-- 
2.17.1