staging: r8712u: Fix possible buffer overrun

In routine r8712_report_sec_ie(), the code could set the length
of the buffer to 256; however, that value is one larger than the
corresponding memory allocation.
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/mlme_linux.c

@@ -156,7 +156,7 @@ void r8712_report_sec_ie(struct _adapter *adapter, u8 authmode, u8 *sec_ie)
 		p = buff;
 		p += sprintf(p, "ASSOCINFO(ReqIEs=");
 		len = sec_ie[1] + 2;
-		len =  (len < IW_CUSTOM_MAX) ? len : IW_CUSTOM_MAX;
+		len =  (len < IW_CUSTOM_MAX) ? len : IW_CUSTOM_MAX - 1;
 		for (i = 0; i < len; i++)
 			p += sprintf(p, "%02x", sec_ie[i]);
 		p += sprintf(p, ")");