function lca('{}'::ltree[]) caused DB Instance crash

HI,Oleg && pgsql-hackers

Plese help me to check this is a bug of ltree?

thxs!

lhl(at)localhost:~$ cat /etc/issue
Ubuntu 14.04.5 LTS \n \l

lhl(at)localhost:~$ uname -av
Linux localhost 3.13.0-107-generic #154-Ubuntu SMP Tue Dec 20 09:57:27 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

lhl(at)localhost:~$ psql mydb
psql (10.3)
Type "help" for help.

mydb=# select version();
version
-------------------------------------------------------------------------------------------------------
PostgreSQL 10.3 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4, 64-bit
(1 row)

mydb=# \dx ltree
List of installed extensions
Name | Version | Schema | Description
-------+---------+--------+-------------------------------------------------
ltree | 1.1 | public | data type for hierarchical tree-like structures
(1 row)

mydb=# select lca('{}'::ltree[]);
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.

in /var/log/syslog

Jul 13 18:02:39 localhost kernel: [25703.907912] postgres[8869]: segfault at 4 ip 00007f6bad8c2ca6 sp 00007fffd8f64560 error 4 in ltree.so[7f6bad8be000+d000]

in log of PostgreSQL Datadir

[lhl mydb psql [local] 2018-07-13 18:02:36.962 CST 8869 5b4878b6.22a5 1 3/2 0]LOG: statement: SELECT e.extname AS "Name", e.extversion AS "Version", n.nspname AS "Schema", c.description AS "Description"
FROM pg_catalog.pg_extension e LEFT JOIN pg_catalog.pg_namespace n ON n.oid = e.extnamespace LEFT JOIN pg_catalog.pg_description c ON c.objoid = e.oid AND c.classoid = 'pg_catalog.pg_extension'::pg_catalog.regclass
WHERE e.extname OPERATOR(pg_catalog.~) '^(ltree)$'
ORDER BY 1;
[lhl mydb psql [local] 2018-07-13 18:02:36.972 CST 8869 5b4878b6.22a5 2 3/0 0]LOG: duration: 10.269 ms
[lhl mydb psql [local] 2018-07-13 18:02:39.313 CST 8869 5b4878b6.22a5 3 3/3 0]LOG: statement: select lca('{}'::ltree[]);
[ 2018-07-13 18:02:39.444 CST 1638 5b481476.666 102 0]LOG: server process (PID 8869) was terminated by signal 11: Segmentation fault
[ 2018-07-13 18:02:39.444 CST 1638 5b481476.666 103 0]DETAIL: Failed process was running: select lca('{}'::ltree[]);
[ 2018-07-13 18:02:39.444 CST 1638 5b481476.666 104 0]LOG: terminating any other active server processes
[lhl mydb [unknown] [local] 2018-07-13 18:02:39.445 CST 8873 5b4878bf.22a9 1 0]FATAL: the database system is in recovery mode
[ 2018-07-13 18:02:39.446 CST 8635 5b4876a7.21bb 1 1/0 0]WARNING: terminating connection because of crash of another server process
[ 2018-07-13 18:02:39.446 CST 8635 5b4876a7.21bb 2 1/0 0]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.
[ 2018-07-13 18:02:39.446 CST 8635 5b4876a7.21bb 3 1/0 0]HINT: In a moment you should be able to reconnect to the database and repeat your command.
[ 2018-07-13 18:02:39.447 CST 1638 5b481476.666 105 0]LOG: archiver process (PID 8636) exited with exit code 1
[ 2018-07-13 18:02:39.447 CST 1638 5b481476.666 106 0]LOG: all server processes terminated; reinitializing
[ 2018-07-13 18:02:39.520 CST 8874 5b4878bf.22aa 1 0]LOG: database system was interrupted; last known up at 2018-07-13 17:53:42 CST
[ 2018-07-13 18:02:39.798 CST 8874 5b4878bf.22aa 2 0]LOG: database system was not properly shut down; automatic recovery in progress
[ 2018-07-13 18:02:39.838 CST 8874 5b4878bf.22aa 3 0]LOG: redo starts at 1/9815F478
[ 2018-07-13 18:02:39.838 CST 8874 5b4878bf.22aa 4 0]LOG: invalid record length at 1/9815F4B0: wanted 24, got 0
[ 2018-07-13 18:02:39.839 CST 8874 5b4878bf.22aa 5 0]LOG: redo done at 1/9815F478
[ 2018-07-13 18:02:40.036 CST 1638 5b481476.666 107 0]LOG: database system is ready to accept connections

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PostgreSQL DBA hailong.li