Subject: equalPolicy() doesn't compare the permissive flag

From: Andreas Lind <[email-masked]>
Date: Thu, 9 Jul 2026 16:28:25 +0200

Hi,

While working on an unrelated RLS patch, I noticed that equalPolicy() in
relcache.c doesn't compare the permissive field of RowSecurityPolicy. It
compares polcmd, hassublinks, policy_name, roles, qual, and
with_check_qual, but not permissive, so two policies that are identical
in every other respect except their PERMISSIVE/RESTRICTIVE designation
are reported as equal.

equalPolicy() is used (via equalRSDesc()) by RelationRebuildRelation()
to decide whether an open relation's existing row-security descriptor
can be kept as-is across a relcache rebuild, or must be treated as
changed. ALTER POLICY has no way to flip a policy's
PERMISSIVE/RESTRICTIVE designation, but DROP POLICY followed by CREATE
POLICY of the same name, roles, command, and quals, differing only in AS
PERMISSIVE/RESTRICTIVE, hits this exactly: the stale descriptor would be
kept, leaving the relcache out of sync with how the policy should now
combine with others (PERMISSIVE policies are ORed together; RESTRICTIVE
policies are ANDed with the rest).

I wasn't able to construct a simple SQL reproduction:
RelationRebuildRelation() (and thus this comparison) is only reached
while the relation is still open (refcount > 0) at the moment its
invalidation is processed. Closing and reopening the relation between
statements -- the usual behavior -- sidesteps the bug, and a second
session can't hold the relation open across the DROP/CREATE either,
since both need AccessExclusiveLock. This looks analogous to
ab6d1cd26eb, which fixed the same kind of omission in this function for
the USING qual and likewise shipped without a test.

Patch attached.

Regards,
Andreas Lind

---

From: Laurenz Albe <[email-masked]>
Date: Fri, 10 Jul 2026 08:58:22 +0200

> the USING qual and likewise shipped without a test.

I don't know if the omission to check for identical PERMISSIVE or
RESTRICTIVE settings can lead to real problems, but I feel that it
violates the promise of the function.  So I am +1 on this change.

Yours,
Laurenz Albe