BUG #17406: Segmentation fault on GiST index after 14.2 upgrade

The following bug has been logged on the website:

Bug reference:      17406
Logged by:          Victor Yegorov
Email address:      vyegorov@gmail.com
PostgreSQL version: 14.2
Operating system:   Ubuntu 18.04.6 LTS (bionic)
Description:

KVM guest, on Intel(R) Xeon(R) CPU E5-2697 v2.

PostgreSQL 12.9 had been upgraded to 14.2 using

pg_upgradecluster -k  -m link 12 main /mnt/postgres/14/

After that, one of the queries is crashing with Segmentation Fault.
However, after REINDEX problem will be fixed. I thought I should report
still.

explain
SELECT r.id, r.name, r.map_center_y, r.map_center_x,
       COALESCE ((SELECT string_agg(id::TEXT, ',') FROM v3_region AS r2
WHERE r2.id != r.id AND r2.ltree_path <@ r.ltree_path), '') AS children
  FROM v3_region AS r;
                                                 QUERY PLAN
-------------------------------------------------------------------------------------------------------------
 Seq Scan on v3_region r  (cost=0.00..3207.31 rows=349 width=580)
   SubPlan 1
     ->  Aggregate  (cost=8.17..8.18 rows=1 width=32)
           ->  Index Scan using region_ltree_path_idx_gist on v3_region r2
(cost=0.14..8.16 rows=1 width=4)
                 Index Cond: (ltree_path <@ r.ltree_path)
                 Filter: (id <> r.id)
(6 rows)

Here is backtrace:
#0  __memmove_sse2_unaligned_erms () at
../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:435
#1  0x00007f129244c266 in memcpy (__len=<optimized out>,
__src=0x55bbbd430f4a, __dest=<optimized out>) at
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:34
#2  copy_ltree (src=0x55bbbd430f4a) at
./build/../contrib/ltree/ltree_gist.c:446
#3  0x00007f129244db51 in gist_ischild (siglen=28, query=0x55bbbd410cb8,
key=0x55bbbd430f18) at ./build/../contrib/ltree/ltree_gist.c:454
#4  ltree_consistent (fcinfo=0x7ffdac2e3e20) at
./build/../contrib/ltree/ltree_gist.c:674
#5  0x000055bbbb944a5d in FunctionCall5Coll
(flinfo=flinfo@entry=0x55bbbd416b20, collation=<optimized out>,
arg1=arg1@entry=140727492165472, arg2=<optimized out>, arg3=<optimized out>,
arg4=<optimized out>, arg5=140727492165471)
    at ./build/../src/backend/utils/fmgr/fmgr.c:1241
#6  0x000055bbbb4db72d in gistindex_keytest (recheck_distances_p=<synthetic
pointer>, recheck_p=<synthetic pointer>, offset=4, page=0x7f1293a45180
"K\313\003", tuple=0x7f1293a47058, scan=0x55bbbd4196c8)
    at ./build/../src/backend/access/gist/gistget.c:222
#7  gistScanPage (scan=scan@entry=0x55bbbd4196c8,
pageItem=pageItem@entry=0x7ffdac2e3fe0, myDistances=myDistances@entry=0x0,
tbm=tbm@entry=0x0, ntids=ntids@entry=0x0) at
./build/../src/backend/access/gist/gistget.c:438
#8  0x000055bbbb4dbf43 in gistgettuple (scan=0x55bbbd4196c8, dir=<optimized
out>) at ./build/../src/backend/access/gist/gistget.c:639
#9  0x000055bbbb50cb05 in index_getnext_tid (scan=0x55bbbd4196c8,
direction=<optimized out>) at
./build/../src/backend/access/index/indexam.c:533
#10 0x000055bbbb50ccbd in index_getnext_slot
(scan=scan@entry=0x55bbbd4196c8,
direction=direction@entry=ForwardScanDirection,
slot=slot@entry=0x55bbbd4057a0) at
./build/../src/backend/access/index/indexam.c:625
#11 0x000055bbbb6a3042 in IndexNext (node=node@entry=0x55bbbd405500) at
./build/../src/backend/executor/nodeIndexscan.c:133
#12 0x000055bbbb688281 in ExecScanFetch (recheckMtd=0x55bbbb6a38a0
<IndexRecheck>, accessMtd=0x55bbbb6a2fd0 <IndexNext>, node=0x55bbbd405500)
at ./build/../src/backend/executor/execScan.c:133
#13 ExecScan (node=0x55bbbd405500, accessMtd=0x55bbbb6a2fd0 <IndexNext>,
recheckMtd=0x55bbbb6a38a0 <IndexRecheck>) at
./build/../src/backend/executor/execScan.c:199
#14 0x000055bbbb685349 in ExecProcNodeInstr (node=0x55bbbd405500) at
./build/../src/backend/executor/execProcnode.c:479
#15 0x000055bbbb68fb9c in ExecProcNode (node=0x55bbbd405500) at
./build/../src/include/executor/executor.h:257
#16 fetch_input_tuple (aggstate=aggstate@entry=0x55bbbd404ed8) at
./build/../src/backend/executor/nodeAgg.c:581
#17 0x000055bbbb692c19 in agg_retrieve_direct (aggstate=0x55bbbd404ed8) at
./build/../src/backend/executor/nodeAgg.c:2364
#18 ExecAgg (pstate=0x55bbbd404ed8) at
./build/../src/backend/executor/nodeAgg.c:2179
#19 0x000055bbbb685349 in ExecProcNodeInstr (node=0x55bbbd404ed8) at
./build/../src/backend/executor/execProcnode.c:479
#20 0x000055bbbb6b14a1 in ExecProcNode (node=0x55bbbd404ed8) at
./build/../src/include/executor/executor.h:257
#21 ExecScanSubPlan (isNull=0x55bbbd4153dd, econtext=0x55bbbd414c00,
node=0x55bbbd415c70) at ./build/../src/backend/executor/nodeSubplan.c:323
#22 ExecSubPlan (node=node@entry=0x55bbbd415c70,
econtext=econtext@entry=0x55bbbd414c00, isNull=0x55bbbd4153dd) at
./build/../src/backend/executor/nodeSubplan.c:89
#23 0x000055bbbb678ebd in ExecEvalSubPlan (state=state@entry=0x55bbbd4153d8,
op=op@entry=0x55bbbd415618, econtext=econtext@entry=0x55bbbd414c00) at
./build/../src/backend/executor/execExprInterp.c:3932
#24 0x000055bbbb679b42 in ExecInterpExpr (state=0x55bbbd4153d8,
econtext=0x55bbbd414c00, isnull=<optimized out>) at
./build/../src/backend/executor/execExprInterp.c:1564
#25 0x000055bbbb6883d2 in ExecEvalExprSwitchContext (isNull=0x7ffdac2e4457,
econtext=0x55bbbd414c00, state=0x55bbbd4153d8) at
./build/../src/include/executor/executor.h:339
#26 ExecProject (projInfo=0x55bbbd4153d0) at
./build/../src/include/executor/executor.h:373
#27 ExecScan (node=<optimized out>, accessMtd=0x55bbbb6afe20 <SeqNext>,
recheckMtd=0x55bbbb6afdf0 <SeqRecheck>) at
./build/../src/backend/executor/execScan.c:238
#28 0x000055bbbb685349 in ExecProcNodeInstr (node=0x55bbbd414af0) at
./build/../src/backend/executor/execProcnode.c:479
#29 0x000055bbbb67e34d in ExecProcNode (node=0x55bbbd414af0) at
./build/../src/include/executor/executor.h:257
#30 ExecutePlan (execute_once=<optimized out>, dest=0x55bbbbdbf260
<donothingDR>, direction=<optimized out>, numberTuples=0,
sendTuples=<optimized out>, operation=CMD_SELECT,
use_parallel_mode=<optimized out>, planstate=0x55bbbd414af0,
    estate=0x55bbbd404c58) at
./build/../src/backend/executor/execMain.c:1551
#31 standard_ExecutorRun (queryDesc=0x55bbbd4037c8, direction=<optimized
out>, count=0, execute_once=<optimized out>) at
./build/../src/backend/executor/execMain.c:361
#32 0x00007f13269e0595 in pgss_ExecutorRun (queryDesc=0x55bbbd4037c8,
direction=ForwardScanDirection, count=0, execute_once=<optimized out>) at
./build/../contrib/pg_stat_statements/pg_stat_statements.c:1003
#33 0x000055bbbb60c3e8 in ExplainOnePlan
(plannedstmt=plannedstmt@entry=0x55bbbd402018, into=into@entry=0x0,
es=es@entry=0x55bbbd2e0f78,
    queryString=queryString@entry=0x55bbbd289148 "explain (analyze, buffers)
SELECT\n", ' ' <repeats 24 times>, "r.id,\n", ' ' <repeats 24 times>,
"r.name,\n", ' ' <repeats 24 times>, "r.map_center_y,\n", ' ' <repeats 24
times>, "r.map_center_x,\n", ' '
<repeats 24 times>..., params=params@entry=0x0, queryEnv=<optimized out>,
planduration=0x7ffdac2e4700, bufusage=0x7ffdac2e4780) at
./build/../src/backend/commands/explain.c:593
#34 0x000055bbbb60c7da in ExplainOneQuery (query=<optimized out>,
cursorOptions=<optimized out>, into=0x0, es=0x55bbbd2e0f78,
    queryString=0x55bbbd289148 "explain (analyze, buffers) SELECT\n", ' '
<repeats 24 times>, "r.id,\n", ' ' <repeats 24 times>, "r.name,\n", ' '
<repeats 24 times>, "r.map_center_y,\n", ' ' <repeats 24 times>,
"r.map_center_x,\n", ' ' <repeats 24 times>..., params=0x0, queryEnv=0x0) at
./build/../src/backend/commands/explain.c:410
#35 0x000055bbbb60ce7d in ExplainQuery (pstate=pstate@entry=0x55bbbd3a0230,
stmt=stmt@entry=0x55bbbd3b7840, params=params@entry=0x0,
dest=dest@entry=0x55bbbd3a01a0) at
./build/../src/backend/commands/explain.c:281
#36 0x000055bbbb806783 in standard_ProcessUtility
(pstmt=pstmt@entry=0x55bbbd3b7fa8,
    queryString=queryString@entry=0x55bbbd289148 "explain (analyze, buffers)
SELECT\n", ' ' <repeats 24 times>, "r.id,\n", ' ' <repeats 24 times>,
"r.name,\n", ' ' <repeats 24 times>, "r.map_center_y,\n", ' ' <repeats 24
times>, "r.map_center_x,\n", ' '
<repeats 24 times>..., readOnlyTree=<optimized out>,
context=context@entry=PROCESS_UTILITY_TOPLEVEL, params=params@entry=0x0,
queryEnv=queryEnv@entry=0x0, dest=0x55bbbd3a01a0, qc=0x7ffdac2e4c70) at
./build/../src/backend/tcop/utility.c:862
#37 0x00007f13269e2221 in pgss_ProcessUtility (pstmt=0x55bbbd3b7fa8,
    queryString=0x55bbbd289148 "explain (analyze, buffers) SELECT\n", ' '
<repeats 24 times>, "r.id,\n", ' ' <repeats 24 times>, "r.name,\n", ' '
<repeats 24 times>, "r.map_center_y,\n", ' ' <repeats 24 times>,
"r.map_center_x,\n", ' ' <repeats 24 times>..., readOnlyTree=<optimized
out>, context=PROCESS_UTILITY_TOPLEVEL, params=0x0, queryEnv=0x0,
dest=0x55bbbd3a01a0, qc=0x7ffdac2e4c70) at
./build/../contrib/pg_stat_statements/pg_stat_statements.c:1135
#38 0x000055bbbb804935 in PortalRunUtility
(portal=portal@entry=0x55bbbd373888, pstmt=0x55bbbd3b7fa8,
isTopLevel=isTopLevel@entry=true,
setHoldSnapshot=setHoldSnapshot@entry=true, dest=dest@entry=0x55bbbd3a01a0,
qc=qc@entry=0x7ffdac2e4c70)
    at ./build/../src/backend/tcop/pquery.c:1155
#39 0x000055bbbb804cab in FillPortalStore
(portal=portal@entry=0x55bbbd373888, isTopLevel=isTopLevel@entry=true) at
./build/../src/backend/tcop/pquery.c:1028
#40 0x000055bbbb8050bf in PortalRun (portal=portal@entry=0x55bbbd373888,
count=count@entry=9223372036854775807, isTopLevel=isTopLevel@entry=true,
run_once=run_once@entry=true, dest=dest@entry=0x55bbbd3cec48,
altdest=altdest@entry=0x55bbbd3cec48,
    qc=0x7ffdac2e4e80) at ./build/../src/backend/tcop/pquery.c:760
#41 0x000055bbbb8008e9 in exec_simple_query (
    query_string=0x55bbbd289148 "explain (analyze, buffers) SELECT\n", ' '
<repeats 24 times>, "r.id,\n", ' ' <repeats 24 times>, "r.name,\n", ' '
<repeats 24 times>, "r.map_center_y,\n", ' ' <repeats 24 times>,
"r.map_center_x,\n", ' ' <repeats 24 times>...) at
./build/../src/backend/tcop/postgres.c:1214
#42 0x000055bbbb802c4c in PostgresMain (argc=argc@entry=1,
argv=argv@entry=0x7ffdac2e5340, dbname=<optimized out>, username=<optimized
out>) at ./build/../src/backend/tcop/postgres.c:4486
#43 0x000055bbbb775e2a in BackendRun (port=<optimized out>, port=<optimized
out>) at ./build/../src/backend/postmaster/postmaster.c:4530
#44 BackendStartup (port=<optimized out>) at
./build/../src/backend/postmaster/postmaster.c:4252
#45 ServerLoop () at ./build/../src/backend/postmaster/postmaster.c:1745
#46 0x000055bbbb776c68 in PostmasterMain (argc=5, argv=0x55bbbd281d90) at
./build/../src/backend/postmaster/postmaster.c:1417
#47 0x000055bbbb4af83b in main (argc=5, argv=0x55bbbd281d90) at
./build/../src/backend/main/main.c:209

I can reproduce the issue easily, if you need more details.