staging: rtl8192e: Fix possible buffer overflow in _rtl92e_wx_set_scan

commit 8687bf9ef9551bcf93897e33364d121667b1aadf upstream.

Function _rtl92e_wx_set_scan calls memcpy without checking the length.
A user could control that length and trigger a buffer overflow.
Fix by checking the length is within the maximum allowed size.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lee Gibson <leegib@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210226145157.424065-1-leegib@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c b/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
index 16bcee1..407effd 100644 (file)
--- a/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
+++ b/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
@@ -406,9 +406,10 @@ static int _rtl92e_wx_set_scan(struct net_device *dev,
                struct iw_scan_req *req = (struct iw_scan_req *)b;
 
                if (req->essid_len) {
-                       ieee->current_network.ssid_len = req->essid_len;
-                       memcpy(ieee->current_network.ssid, req->essid,
-                              req->essid_len);
+                       int len = min_t(int, req->essid_len, IW_ESSID_MAX_SIZE);
+
+                       ieee->current_network.ssid_len = len;
+                       memcpy(ieee->current_network.ssid, req->essid, len);
                }
        }