[tor-bugs] #11304 [Tor]: connection_write_to_buf_impl_() might incorrectly call connection_mark_for_close() on an orconn

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#11304: connection_write_to_buf_impl_() might incorrectly call
connection_mark_for_close() on an orconn
--------------------+------------------------------------
 Reporter:  andrea  |          Owner:  andrea
     Type:  defect  |         Status:  new
 Priority:  normal  |      Milestone:  Tor: 0.2.5.x-final
Component:  Tor     |        Version:  Tor: 0.2.5.3-alpha
 Keywords:          |  Actual Points:
Parent ID:          |         Points:
--------------------+------------------------------------
 The function connection_write_to_buf_impl_() in connection.c contains this
 code:

 {{{
 old_datalen = buf_datalen(conn->outbuf);
 if (zlib) {
   dir_connection_t *dir_conn = TO_DIR_CONN(conn);
   int done = zlib < 0;
   CONN_LOG_PROTECT(conn, r = write_to_buf_zlib(conn->outbuf,
                                                dir_conn->zlib_state,
                                                string, len, done));
 } else {
   CONN_LOG_PROTECT(conn, r = write_to_buf(string, len, conn->outbuf));
 }
 if (r < 0) {
   if (CONN_IS_EDGE(conn)) {
     /* if it failed, it means we have our package/delivery windows set
        wrong compared to our max outbuf size. close the whole circuit. */
     log_warn(LD_NET,
              "write_to_buf failed. Closing circuit (fd %d).",
 (int)conn->s);
     circuit_mark_for_close(circuit_get_by_edge_conn(TO_EDGE_CONN(conn)),
                            END_CIRC_REASON_INTERNAL);
   } else {
     log_warn(LD_NET,
              "write_to_buf failed. Closing connection (fd %d).",
              (int)conn->s);
              connection_mark_for_close(conn);
   }
   return;
 }
 }}}

 If conn is an orconn and write_to_buf() or write_to_buf_zlib() ever fails,
 this call to connection_mark_for_close() will incorrectly close it out
 from under the channel layer.  This should test for orconns and use
 connection_or_close_for_error() instead in that case.  Created pursuant to
 connection_mark_for_close() audit task #7472.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/11304>
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