BUG #19836: Backend crash with large hash partition modulus

The following bug has been logged on the website:

Bug reference: 19836
Logged by: Sumedh Pathak
Email address: sumedhpathak(at)gmail(dot)com
PostgreSQL version: 19rc1
Operating system: MacOS
Description:

Hi,

The following SQL crashes PostgreSQL 20devel (72b9498df9a, macOS ARM64):
CREATE TABLE parent (i integer) PARTITION BY HASH (i);
CREATE TABLE p0 PARTITION OF parent
FOR VALUES WITH (MODULUS 3, REMAINDER 0);
CREATE TABLE p1 PARTITION OF parent
FOR VALUES WITH (MODULUS 2147483646, REMAINDER 2);

The third statement causes a crash and server recovery. In
check_new_partition_bound(), remainder += spec->modulus overflows signed int
(2 + 2147483646), leading to an out-of-bounds lookup. The crash was verified
on PG 17,18 as well, but it seems like it exists since PG11.

Thanks.