Re: BUG #18533: pg_basebackup uses out-of-bounds memory and a segment error occurs during backup

PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> The following bug has been logged on the website:
> Bug reference: 18533
> Logged by: ji xiaohang
> Email address: 1165125080(at)qq(dot)com
> PostgreSQL version: 16.3
> Operating system: centos 7
> Description:

> pg_basebackup uses out-of-bounds memory and a segment error occurs during
> backup

> Run the following command to back up the pg11 database using the
> pg_basebackup backup tool of the pg16 version:
> pg_basebackup -h 127.0.0.1 -p 56100 -U Backup -F tar -X f -z -c fast -P -v
> -D - > base.tar.gz
> The segmentation fault does not recur after I run commands. It seems that
> this problem recurs only in my service invoking scenario.

FWIW, I tried and failed to reproduce this problem. I don't see any
segfault, nor does running pg_basebackup under Valgrind report any
invalid accesses. Perhaps it's dependent on the contents of the
source installation? (My test was with v11's core regression database
and not much else.)

It's going to be hard to convince people that we should change
anything if we can't duplicate the problem, so I'd suggest working
harder to make a self-contained reproducer.

regards, tom lane