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From:   gregkh@linuxfoundation.org
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH 4.19 093/120] staging: ks7010: prevent buffer overflow in ks_wlan_set_scan()
Date:   Mon, 15 Mar 2021 14:57:24 +0100
Message-Id: <20210315135723.019585083@linuxfoundation.org>
In-Reply-To: <20210315135720.002213995@linuxfoundation.org>
References: <20210315135720.002213995@linuxfoundation.org>
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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

From: Dan Carpenter <dan.carpenter@oracle.com>

commit e163b9823a0b08c3bb8dc4f5b4b5c221c24ec3e5 upstream.

The user can specify a "req->essid_len" of up to 255 but if it's
over IW_ESSID_MAX_SIZE (32) that can lead to memory corruption.

Fixes: 13a9930d15b4 ("staging: ks7010: add driver from Nanonote extra-repository")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YD4fS8+HmM/Qmrw6@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/ks7010/ks_wlan_net.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/staging/ks7010/ks_wlan_net.c
+++ b/drivers/staging/ks7010/ks_wlan_net.c
@@ -1120,6 +1120,7 @@ static int ks_wlan_set_scan(struct net_d
 {
 	struct ks_wlan_private *priv = netdev_priv(dev);
 	struct iw_scan_req *req = NULL;
+	int len;
 
 	if (priv->sleep_mode == SLP_SLEEP)
 		return -EPERM;
@@ -1129,8 +1130,9 @@ static int ks_wlan_set_scan(struct net_d
 	if (wrqu->data.length == sizeof(struct iw_scan_req) &&
 	    wrqu->data.flags & IW_SCAN_THIS_ESSID) {
 		req = (struct iw_scan_req *)extra;
-		priv->scan_ssid_len = req->essid_len;
-		memcpy(priv->scan_ssid, req->essid, priv->scan_ssid_len);
+		len = min_t(int, req->essid_len, IW_ESSID_MAX_SIZE);
+		priv->scan_ssid_len = len;
+		memcpy(priv->scan_ssid, req->essid, len);
 	} else {
 		priv->scan_ssid_len = 0;
 	}