@@ -111,6 +111,17 @@ typedef struct {

     HANDLE device;

 } ring_buffer_handles_t;

+typedef union {

+    message_header_t header;

+    address_message_t address;

+    route_message_t route;

+    flush_neighbors_message_t flush_neighbors;

+    block_dns_message_t block_dns;

+    dns_cfg_message_t dns;

+    enable_dhcp_message_t dhcp;

+    register_ring_buffers_message_t rrb;

+    set_mtu_message_t mtu;

+} pipe_message_t;

 static DWORD

 AddListItem(list_item_t **pfirst, LPVOID data)

@@ -1444,18 +1455,7 @@ static VOID

 HandleMessage(HANDLE pipe, HANDLE ovpn_proc, ring_buffer_handles_t *ring_buffer_handles,

               DWORD bytes, DWORD count, LPHANDLE events, undo_lists_t *lists)

 {

-    DWORD read;

-    union {

-        message_header_t header;

-        address_message_t address;

-        route_message_t route;

-        flush_neighbors_message_t flush_neighbors;

-        block_dns_message_t block_dns;

-        dns_cfg_message_t dns;

-        enable_dhcp_message_t dhcp;

-        register_ring_buffers_message_t rrb;

-        set_mtu_message_t mtu;

-    } msg;

+    pipe_message_t msg;

     ack_message_t ack = {

         .header = {

             .type = msg_acknowledgement,

@@ -1465,7 +1465,7 @@ HandleMessage(HANDLE pipe, HANDLE ovpn_proc, ring_buffer_handles_t *ring_buffer_

         .error_number = ERROR_MESSAGE_DATA

     };

-    read = ReadPipeAsync(pipe, &msg, bytes, count, events);

+    DWORD read = ReadPipeAsync(pipe, &msg, bytes, count, events);

     if (read != bytes || read < sizeof(msg.header) || read != msg.header.size)

     {

         goto out;

@@ -1884,6 +1884,13 @@ RunOpenvpn(LPVOID p)

             break;

         }

+        if (bytes > sizeof(pipe_message_t))

+        {

+            /* process at the other side of the pipe is misbehaving, shut it down */

+            MsgToEventLog(MSG_FLAGS_ERROR, TEXT("OpenVPN process sent too large payload length to the pipe (%lu bytes), it will be terminated"), bytes);

+            break;

+        }

+

         HandleMessage(ovpn_pipe, proc_info.hProcess, &ring_buffer_handles, bytes, 1, &exit_event, &undo_lists);

     }