[PATCH] Fix null pointer dereference in PG19

Aleksander Alekseev <aleksander@tigerdata.com>

From: Aleksander Alekseev <aleksander@tigerdata.com>

To: PostgreSQL Development <pgsql-hackers@postgresql.org>

Date: 2026-04-21T13:40:49Z

Lists: pgsql-hackers

Attachments

stacktrace.txt (text/plain)
crash.sql (application/sql)
v1-0001-Forbid-FOR-PORTION-OF-on-views-with-INSTEAD-OF-tr.patch (text/x-patch) patch v1-0001

Hi,

I discovered that it's possible to crash Postgres when using VIEWS,
FOR PORTION OF syntax and INSTEAD OF triggers together. See crash.sql.

This happens because in ExecModifyTable() around line 4827 there is no
check for `relkind == RELKIND_VIEW`. If this is the case `tupleid`
ends up being NULL which causes null pointer dereference later when
ExecDeleteEpilogue() or ExecUpdateEpilogue() calls
ExecForPortionOfLeftovers() with tupleid = NULL. An example stacktrace
is attached.

I propose fixing this by explicitly forbidding using the named
features together. See the patch.


-- 
Best regards,
Aleksander Alekseev