Horton

Re: BUG #18974: Postgresql repeatable crash after pg_upgrade from 15 to 17.5 version in postgresql_fdw queries

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Sergei Kornilov <sk@zsrv.org>
Cc: Maxim Boguk <maxim.boguk@gmail.com>, pgsql-bugs@lists.postgresql.org
Date: 2025-07-02T19:21:50Z
Lists: pgsql-bugs

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  1. Correctly copy the target host identification in PQcancelCreate.

Sergei Kornilov <sk@zsrv.org> writes:
> Yeah, I think there is a missing copy of the type field:

> --- a/src/interfaces/libpq/fe-cancel.c
> +++ b/src/interfaces/libpq/fe-cancel.c
> @@ -119,6 +119,7 @@ PQcancelCreate(PGconn *conn)
>          goto oom_error;
 
>      originalHost = conn->connhost[conn->whichhost];
> +    cancelConn->connhost[0].type = originalHost.type;
>      if (originalHost.host)
>      {
>          cancelConn->connhost[0].host = strdup(originalHost.host);

> Other fields of the pg_conn_host structure are copied below in the code, excepts type.

Good catch!

For the archives: it's easy to reproduce this crash by modifying
the postgres_fdw regression tests, along the lines of

diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index e534b40de3c..883dc669deb 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -8,7 +8,7 @@ CREATE SERVER testserver1 FOREIGN DATA WRAPPER postgres_fdw;
 DO $d$
     BEGIN
         EXECUTE $$CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw
-            OPTIONS (dbname '$$||current_database()||$$',
+            OPTIONS (hostaddr '127.0.0.1', dbname '$$||current_database()||$$',
                      port '$$||current_setting('port')||$$'
             )$$;
         EXECUTE $$CREATE SERVER loopback2 FOREIGN DATA WRAPPER postgres_fdw

I'll see to fixing this.

			regards, tom lane