valgrind error

I was just trying to revive lousyjack, my valgrind buildfarm animal
which has been offline for 12 days, after having upgraded the machine
(fedora 31, gcc 9.3.1, valgrind 3.15) and noticed lots of errors like this:

2020-04-17 19:26:03.483 EDT [63741:3] pg_regress LOG:  statement: CREATE
DATABASE "regression" TEMPLATE=template0
==63717== VALGRINDERROR-BEGIN
==63717== Use of uninitialised value of size 8
==63717==    at 0xAC5BB5: pg_comp_crc32c_sb8 (pg_crc32c_sb8.c:82)
==63717==    by 0x55A98B: XLogRecordAssemble (xloginsert.c:785)
==63717==    by 0x55A268: XLogInsert (xloginsert.c:461)
==63717==    by 0x8BC9E0: LogCurrentRunningXacts (standby.c:1005)
==63717==    by 0x8BC8F9: LogStandbySnapshot (standby.c:961)
==63717==    by 0x550CB3: CreateCheckPoint (xlog.c:8937)
==63717==    by 0x82A3B2: CheckpointerMain (checkpointer.c:441)
==63717==    by 0x56347D: AuxiliaryProcessMain (bootstrap.c:453)
==63717==    by 0x83CA18: StartChildProcess (postmaster.c:5474)
==63717==    by 0x83A120: reaper (postmaster.c:3045)
==63717==    by 0x4874B1F: ??? (in /usr/lib64/libpthread-2.30.so)
==63717==    by 0x5056F29: select (in /usr/lib64/libc-2.30.so)
==63717==    by 0x8380A0: ServerLoop (postmaster.c:1691)
==63717==    by 0x837A1F: PostmasterMain (postmaster.c:1400)
==63717==    by 0x74A71D: main (main.c:210)
==63717==  Uninitialised value was created by a stack allocation
==63717==    at 0x8BC942: LogCurrentRunningXacts (standby.c:984)
==63717==
==63717== VALGRINDERROR-END
{
   <insert_a_suppression_name_here>
   Memcheck:Value8
   fun:pg_comp_crc32c_sb8
   fun:XLogRecordAssemble
   fun:XLogInsert
   fun:LogCurrentRunningXacts
   fun:LogStandbySnapshot
   fun:CreateCheckPoint
   fun:CheckpointerMain
   fun:AuxiliaryProcessMain
   fun:StartChildProcess
   fun:reaper
   obj:/usr/lib64/libpthread-2.30.so
   fun:select
   fun:ServerLoop
   fun:PostmasterMain
   fun:main
}

I can't see what the problem is immediately.

cheers

andrew

--
Andrew Dunstan https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services