BUG #17563: exception " Segmentation fault" occured when i executed 'reindex index concurrently' in pg12.0

The following bug has been logged on the website:

Bug reference:      17563
Logged by:          Melody Liu
Email address:      melody_xiaodi@sina.com
PostgreSQL version: 12.0
Operating system:   CentOS Linux release 7.7.1908 (Core)
Description:

i executed the sql below to rebuild an index in my pg database(version 12.0)
:
psql> reindex index concurrently myindex;
an unexpectend error was reported and all of the client processes exited
abnormally .
error messages in pg logs:
db=,user=,app=,client=LOG:  00000: server process (PID 36031) was terminated
by signal 11: Segmentation fault
db=,user=,app=,client=DETAIL:  Failed process was running: reindex index
concurrently public.myindex;

the relative errors in system log(/var/log/message):
kernel: postgres[36031]: segfault at 34 ip 00000000007494de sp
00007ffc8e6d6550 error 4 in postgres[400000+72e000]

then i run the os command: 'addr2line -e /usr/pgsql-12/bin/postgres
00000000007494de -f' and the output was:
WaitForLockersMultiple