BUG #16144: Segmentation fault on dict_int extension

The following bug has been logged on the website:

Bug reference:      16144
Logged by:          cili
Email address:      [email protected]
PostgreSQL version: 12.1
Operating system:   CentOS 7.4
Description:        

The dict_int extension is an example of an add-on dictionary template for
full-text search. The 'intdict' is a built-in dictionary. If we set MAXLEN
parameter with negative value for the dictionary, ts_lexize function causes
a segmentation fault. The negative limit for MAXLEN which causes
segmentation fault is environment dependent. 

# initdb
# pg_ctl -D /var/lib/pgsql/data -l logfile start
# psql

postgres=# CREATE EXTENSION dict_int;
CREATE EXTENSION
postgres=# ALTER TEXT SEARCH DICTIONARY intdict (MAXLEN = -214783648);
ALTER TEXT SEARCH DICTIONARY
postgres=# select ts_lexize('intdict', '12345678');
server closed the connection unexpectedly
	This probably means the server terminated abnormally
	before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!>
!>\q

# cat /var/lib/pgsql/data/pg_log/postgresql-Mon.log
LOG:  database system was shut down at 2019-12-02 12:05:17 UTC
LOG:  database system is ready to accept connections
LOG:  autovacuum launcher started
LOG:  server process (PID 5288) was terminated by signal 11: Segmentation
fault
DETAIL:  Failed process was running: select ts_lexize('intdict',
'12345678');
LOG:  terminating any other active server processes
WARNING:  terminating connection because of crash of another server
process
DETAIL:  The postmaster has commanded this server process to roll back the
current transaction and exit, because another server process exited
abnormally and possibly corrupted shared memory.
HINT:  In a moment you should be able to reconnect to the database and
repeat your command.
LOG:  all server processes terminated; reinitializing
FATAL:  the database system is in recovery mode
LOG:  database system was interrupted; last known up at 2019-12-02 12:05:24
UTC
LOG:  database system was not properly shut down; automatic recovery in
progress
LOG:  redo starts at 0/180D7F8
LOG:  record with zero length at 0/1822720
LOG:  redo done at 0/18226F0
LOG:  last completed transaction was at log time 2019-12-02
12:05:42.199372+00
LOG:  database system is ready to accept connections
LOG:  autovacuum launcher started