BUG #17280: global-buffer-overflow on select from pg_stat_slru

The following bug has been logged on the website:

Bug reference: 17280
Logged by: Alexander Kozhemyakin
Email address: a(dot)kozhemyakin(at)postgrespro(dot)ru
PostgreSQL version: 14.0
Operating system: Ubuntu 21.04
Description:

The following simple query:
select * from pg_catalog.pg_stat_slru
leads to the sanitizer-detected error:
==23911==ERROR: AddressSanitizer: global-buffer-overflow on address
0x5582bec7c5e0 at pc 0x5582bbd2c01c bp 0x7fff0b73a470 sp 0x7fff0b73a460
READ of size 64 at 0x5582bec7c5e0 thread T0
#0 0x5582bbd2c01b in pg_stat_get_slru
/home/postgres/postgres/src/backend/utils/adt/pgstatfuncs.c:1914
#1 0x5582bb405b83 in ExecMakeTableFunctionResult
/home/postgres/postgres/src/backend/executor/execSRF.c:234
#2 0x5582bb45dfd5 in FunctionNext
/home/postgres/postgres/src/backend/executor/nodeFunctionscan.c:95
#3 0x5582bb408a6f in ExecScanFetch
/home/postgres/postgres/src/backend/executor/execScan.c:133
#4 0x5582bb408cba in ExecScan
/home/postgres/postgres/src/backend/executor/execScan.c:182
#5 0x5582bb45db99 in ExecFunctionScan
/home/postgres/postgres/src/backend/executor/nodeFunctionscan.c:270
#6 0x5582bb3fd916 in ExecProcNodeFirst
/home/postgres/postgres/src/backend/executor/execProcnode.c:463
#7 0x5582bb3ddf35 in ExecProcNode
../../../src/include/executor/executor.h:257
#8 0x5582bb3ddf35 in ExecutePlan
/home/postgres/postgres/src/backend/executor/execMain.c:1551
#9 0x5582bb3de54b in standard_ExecutorRun
/home/postgres/postgres/src/backend/executor/execMain.c:361
#10 0x5582bb3de75a in ExecutorRun
/home/postgres/postgres/src/backend/executor/execMain.c:305
#11 0x5582bbabc326 in PortalRunSelect
/home/postgres/postgres/src/backend/tcop/pquery.c:921
#12 0x5582bbac25e3 in PortalRun
/home/postgres/postgres/src/backend/tcop/pquery.c:765
#13 0x5582bbab6277 in exec_simple_query
/home/postgres/postgres/src/backend/tcop/postgres.c:1214
#14 0x5582bbabb2e1 in PostgresMain
/home/postgres/postgres/src/backend/tcop/postgres.c:4497
#15 0x5582bb86dadd in BackendRun
/home/postgres/postgres/src/backend/postmaster/postmaster.c:4584
#16 0x5582bb876e01 in BackendStartup
/home/postgres/postgres/src/backend/postmaster/postmaster.c:4312
#17 0x5582bb8775a9 in ServerLoop
/home/postgres/postgres/src/backend/postmaster/postmaster.c:1801
#18 0x5582bb879d6f in PostmasterMain
/home/postgres/postgres/src/backend/postmaster/postmaster.c:1473
#19 0x5582bb563465 in main
/home/postgres/postgres/src/backend/main/main.c:198
#20 0x7fac88170564 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x28564)
#21 0x5582baba0ded in _start
(/home/postgres/rel_master/bin/postgres+0x1a72ded)

0x5582bec7c5e0 is located 32 bytes to the left of global variable 'walStats'
defined in 'pgstat.c:282:24' (0x5582bec7c600) of size 72
0x5582bec7c5e0 is located 0 bytes to the right of global variable
'slruStats' defined in 'pgstat.c:283:25' (0x5582bec7c3e0) of size 512
SUMMARY: AddressSanitizer: global-buffer-overflow
/home/postgres/postgres/src/backend/utils/adt/pgstatfuncs.c:1914 in
pg_stat_get_slru
Shadow bytes around the buggy address:
0x0ab0d7d87860: f9 f9 f9 f9 00 00 f9 f9 f9 f9 f9 f9 00 f9 f9 f9
0x0ab0d7d87870: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
0x0ab0d7d87880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ab0d7d87890: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0ab0d7d878a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0ab0d7d878b0: 00 00 00 00 00 00 00 00 00 00 00 00[f9]f9 f9 f9
0x0ab0d7d878c0: 00 00 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9
0x0ab0d7d878d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 f9 f9 f9
0x0ab0d7d878e0: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
0x0ab0d7d878f0: 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9
0x0ab0d7d87900: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc