Re: BUG #19382: Server crash at __nss_database_lookup

On Tue, 20 Jan 2026 at 14:15, Kirill Reshke <reshkekirill(at)gmail(dot)com> wrote:
>
> On Tue, 20 Jan 2026 at 13:58, PG Bug reporting form
> <noreply(at)postgresql(dot)org> wrote:
> >
> > The following bug has been logged on the website:
> >
> > Bug reference: 19382
> > Logged by: Yuxiao Guo
> > Email address: dllggyx(at)outlook(dot)com
> > PostgreSQL version: 17.7
> > Operating system: Ubuntu 20.04 x86-64, docker image postgres:17.7
> > Description:
> >
> > Hi, I found a crash in PostgreSQL. Here are the details:
> >
> > PoC:
> > DROP FUNCTION IF EXISTS bar();
> > DROP TYPE IF EXISTS foo CASCADE;
> > CREATE TYPE foo AS (a INT, b INT);
> > CREATE FUNCTION bar() RETURNS RECORD AS $$
> > DECLARE
> > r foo := ROW(123, power(2, 30));
> > BEGIN
> > ALTER TYPE foo ALTER ATTRIBUTE b TYPE TEXT;
> > RETURN r;
> > END;
> > $$ LANGUAGE plpgsql;
> > SELECT bar();
> >
> > DROP TYPE IF EXISTS foo CASCADE;
> > CREATE TYPE foo AS (a INT, b INT);
> > BEGIN;
> > DECLARE c CURSOR FOR SELECT (i, power(2, 30))::foo FROM
> > generate_series(1,10) i;
> > FETCH c;
> > ALTER TYPE foo ALTER ATTRIBUTE b TYPE TEXT;
> > FETCH c;
> > COMMIT;
> >
> >
> > Stacktrace:
> > #0 0x7182a7813b38 (__nss_database_lookup+0x284b8)
> > #1 0x91c9e5 (textout+0x85)
> > #2 0x94cbd3 (OutputFunctionCall+0x33)
> > #3 0x8db524 (record_out+0x244)
> > #4 0x94cbd3 (OutputFunctionCall+0x33)
> > #5 0x49fafc (printtup+0x2bc)
> > #6 0x7fc888 (RunFromStore+0xa8)
> > #7 0x7fbeb5 (PortalRunSelect+0x75)
> > #8 0x7fbbbe (PortalRun+0x16e)
> > #9 0x7fadd5 (exec_simple_query+0x585)
> > #10 0x7f8929 (PostgresMain+0x949)
> > #11 0x7f45bf (BackendMain+0x3f)
> > #12 0x75df24 (postmaster_child_launch+0x94)
> > #13 0x762101 (ServerLoop+0x1d61)
> > #14 0x75faab (PostmasterMain+0xd8b)
> > #15 0x6a3349 (main+0x2f9)
> > #16 0x7182a76ac083 (__libc_start_main+0xf3)
> > #17 0x49006e (_start+0x2e)
> >
> >
> >
> >
>
> reproduced here on HEAD
>

In fact, this fails as fast as 'SELECT bar()' for me. Also, it fails
for REL_14_STABLE, REL_16_STABLE, so, problem is for all supported
versions

--
Best regards,
Kirill Reshke