Invalidate plan cache after role changes.

Role membership, role attribute, and database ownership changes may
impact the expected behavior of row-level security policies, but
currently the plan cache doesn't take notice.  To fix, register
syscache callbacks on pg_auth_members, pg_authid, and pg_database
that invalidate the role-dependent plans.  Changes to other
databases' pg_database rows are ignored.

Reported-by: Ilya Staroverov <i.staroverov@ftdata.ru>
Reported-by: Shinya Kato <shinya11.kato@gmail.com>
Author: Ilya Staroverov <i.staroverov@ftdata.ru>
Author: Shinya Kato <shinya11.kato@gmail.com>
Co-authored-by: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Security: CVE-2026-14666
Backpatch-through: 14

src/backend/utils/adt/acl.c

@@ -77,7 +77,7 @@ enum RoleRecurseType
 };
 static Oid	cached_role[] = {InvalidOid, InvalidOid, InvalidOid};
 static List *cached_roles[] = {NIL, NIL, NIL};
-static uint32 cached_db_hash;
+uint32		cached_db_hash;
 
 /*
  * If the list of roles gathered by roles_is_member_of() grows larger than the

src/backend/utils/cache/plancache.c

@@ -36,7 +36,10 @@
  * certain other system catalogs, such as pg_namespace; but for them, our
  * response is just to invalidate all plans.  We expect updates on those
  * catalogs to be infrequent enough that more-detailed tracking is not worth
- * the effort.
+ * the effort.  We likewise watch pg_authid, pg_auth_members, and
+ * pg_database, which can change which row-level security policies apply.
+ * Since those are shared catalogs whose inval events reach every backend
+ * in the cluster, we invalidate only the role-dependent plans.
  *
  * In addition to full-fledged query plans, we provide a facility for
  * detecting invalidations of simple scalar expressions.  This is fairly
@@ -66,6 +69,7 @@
 #include "storage/lmgr.h"
 #include "tcop/pquery.h"
 #include "tcop/utility.h"
+#include "utils/acl.h"
 #include "utils/inval.h"
 #include "utils/memutils.h"
 #include "utils/resowner.h"
@@ -116,6 +120,7 @@ static bool ScanQueryWalker(Node *node, bool *acquire);
 static TupleDesc PlanCacheComputeResultDesc(List *stmt_list);
 static void PlanCacheRelCallback(Datum arg, Oid relid);
 static void PlanCacheObjectCallback(Datum arg, int cacheid, uint32 hashvalue);
+static void PlanCacheRoleCallback(Datum arg, int cacheid, uint32 hashvalue);
 static void PlanCacheSysCallback(Datum arg, int cacheid, uint32 hashvalue);
 
 /* ResourceOwner callbacks to track plancache references */
@@ -162,6 +167,9 @@ InitPlanCache(void)
 	CacheRegisterSyscacheCallback(AMOPOPID, PlanCacheSysCallback, (Datum) 0);
 	CacheRegisterSyscacheCallback(FOREIGNSERVEROID, PlanCacheSysCallback, (Datum) 0);
 	CacheRegisterSyscacheCallback(FOREIGNDATAWRAPPEROID, PlanCacheSysCallback, (Datum) 0);
+	CacheRegisterSyscacheCallback(AUTHMEMROLEMEM, PlanCacheRoleCallback, (Datum) 0);
+	CacheRegisterSyscacheCallback(AUTHOID, PlanCacheRoleCallback, (Datum) 0);
+	CacheRegisterSyscacheCallback(DATABASEOID, PlanCacheRoleCallback, (Datum) 0);
 }
 
 /*
@@ -2168,6 +2176,56 @@ PlanCacheObjectCallback(Datum arg, int cacheid, uint32 hashvalue)
 	}
 }
 
+/*
+ * PlanCacheRoleCallback
+ *		Syscache inval callback function for AUTHMEMROLEMEM, AUTHOID, and
+ *		DATABASEOID caches
+ *
+ * Role membership, role attributes, and database ownership (which confers
+ * membership in pg_database_owner) affect planning by way of row-level
+ * security, so invalidate just the role-dependent plans.  For DATABASEOID, we
+ * can ignore changes to other databases' pg_database rows.
+ */
+static void
+PlanCacheRoleCallback(Datum arg, int cacheid, uint32 hashvalue)
+{
+	dlist_iter	iter;
+
+	if (cacheid == DATABASEOID &&
+		hashvalue != cached_db_hash &&
+		hashvalue != 0)
+		return;					/* ignore pg_database changes for other DBs */
+
+	dlist_foreach(iter, &saved_plan_list)
+	{
+		CachedPlanSource *plansource = dlist_container(CachedPlanSource,
+													   node, iter.cur);
+
+		Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
+
+		/* No work if it's already invalidated */
+		if (!plansource->is_valid)
+			continue;
+
+		/* Never invalidate if parse/plan would be a no-op anyway */
+		if (!StmtPlanRequiresRevalidation(plansource))
+			continue;
+
+		if (plansource->dependsOnRLS)
+		{
+			/* Invalidate the querytree and generic plan */
+			plansource->is_valid = false;
+			if (plansource->gplan)
+				plansource->gplan->is_valid = false;
+		}
+		else if (plansource->gplan && plansource->gplan->dependsOnRole)
+		{
+			/* Invalidate the generic plan only */
+			plansource->gplan->is_valid = false;
+		}
+	}
+}
+
 /*
  * PlanCacheSysCallback
  *		Syscache inval callback function for other caches

src/include/utils/acl.h

@@ -227,6 +227,9 @@ extern void select_best_grantor(Oid roleId, AclMode privileges,
 								const Acl *acl, Oid ownerId,
 								Oid *grantorId, AclMode *grantOptions);
 
+/* DATABASEOID syscache hash value for our own database, set by initialize_acl */
+extern uint32 cached_db_hash;
+
 extern void initialize_acl(void);
 
 /*