stop assuming that our downcasts have a struct offset of 0

shouldn't actually change anything, but who knows.

src/or/circuitlist.c

@@ -504,7 +504,7 @@ circuit_free(circuit_t *circ)
    * "active" checks will be violated. */
   cell_queue_clear(&circ->n_conn_cells);
 
-  memset(circ, 0xAA, memlen); /* poison memory */
+  memset(mem, 0xAA, memlen); /* poison memory */
   tor_free(mem);
 }
 

src/or/connection.c

@@ -423,7 +423,7 @@ _connection_free(connection_t *conn)
     connection_or_remove_from_identity_map(TO_OR_CONN(conn));
   }
 
-  memset(conn, 0xAA, memlen); /* poison memory */
+  memset(mem, 0xAA, memlen); /* poison memory */
   tor_free(mem);
 }