Correctly update hasSubLinks while mutating a rule action.

tglsfdc · tglsfdc · commit b4110bdbfe9d · 2023-06-13T15:58:37.000-04:00
rewriteRuleAction neglected to check for SubLink nodes in the securityQuals of range table entries. This could lead to failing to convert such a SubLink to a SubPlan, resulting in assertion crashes or weird errors later in planning. In passing, fix some poor coding in rewriteTargetView: we should not pass the source parsetree's hasSubLinks field to ReplaceVarsFromTargetList's outer_hasSubLinks. ReplaceVarsFromTargetList knows enough to ignore that when a Query node is passed, but it's still confusing and bad precedent: if we did try to update that flag we'd be updating a stale copy of the parsetree. Per bug #17972 from Alexander Lakhin. This has been broken since we added RangeTblEntry.securityQuals (although the presented test case only fails back to 215b43c), so back-patch all the way. Discussion: https://postgr.es/m/17972-f422c094237847d0@postgresql.org
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
@@ -472,6 +472,8 @@ rewriteRuleAction(Query *parsetree,
 					/* other RTE types don't contain bare expressions */
 					break;
 			}
+			sub_action->hasSubLinks |=
+				checkExprHasSubLink((Node *) rte->securityQuals);
 			if (sub_action->hasSubLinks)
 				break;			/* no need to keep scanning rtable */
 		}
@@ -3304,7 +3306,7 @@ rewriteTargetView(Query *parsetree, Relation view)
 								  view_targetlist,
 								  REPLACEVARS_REPORT_ERROR,
 								  0,
-								  &parsetree->hasSubLinks);
+								  NULL);
 
 	/*
 	 * Update all other RTI references in the query that point to the view
diff --git a/src/test/regress/expected/updatable_views.out b/src/test/regress/expected/updatable_views.out
@@ -2616,6 +2616,38 @@ DROP VIEW v1;
 DROP TABLE t2;
 DROP TABLE t1;
 --
+-- Test sub-select in nested security barrier views, per bug #17972
+--
+CREATE TABLE t1 (a int);
+CREATE VIEW v1 WITH (security_barrier = true) AS
+  SELECT * FROM t1;
+CREATE RULE v1_upd_rule AS ON UPDATE TO v1 DO INSTEAD
+  UPDATE t1 SET a = NEW.a WHERE a = OLD.a;
+CREATE VIEW v2 WITH (security_barrier = true) AS
+  SELECT * FROM v1 WHERE EXISTS (SELECT 1);
+EXPLAIN (COSTS OFF) UPDATE v2 SET a = 1;
+                    QUERY PLAN                     
+---------------------------------------------------
+ Update on t1
+   InitPlan 1 (returns $0)
+     ->  Result
+   ->  Merge Join
+         Merge Cond: (t1.a = v1.a)
+         ->  Sort
+               Sort Key: t1.a
+               ->  Seq Scan on t1
+         ->  Sort
+               Sort Key: v1.a
+               ->  Subquery Scan on v1
+                     ->  Result
+                           One-Time Filter: $0
+                           ->  Seq Scan on t1 t1_1
+(14 rows)
+
+DROP VIEW v2;
+DROP VIEW v1;
+DROP TABLE t1;
+--
 -- Test CREATE OR REPLACE VIEW turning a non-updatable view into an
 -- auto-updatable view and adding check options in a single step
 --
diff --git a/src/test/regress/sql/updatable_views.sql b/src/test/regress/sql/updatable_views.sql
@@ -1243,6 +1243,23 @@ DROP VIEW v1;
 DROP TABLE t2;
 DROP TABLE t1;
 
+--
+-- Test sub-select in nested security barrier views, per bug #17972
+--
+CREATE TABLE t1 (a int);
+CREATE VIEW v1 WITH (security_barrier = true) AS
+  SELECT * FROM t1;
+CREATE RULE v1_upd_rule AS ON UPDATE TO v1 DO INSTEAD
+  UPDATE t1 SET a = NEW.a WHERE a = OLD.a;
+CREATE VIEW v2 WITH (security_barrier = true) AS
+  SELECT * FROM v1 WHERE EXISTS (SELECT 1);
+
+EXPLAIN (COSTS OFF) UPDATE v2 SET a = 1;
+
+DROP VIEW v2;
+DROP VIEW v1;
+DROP TABLE t1;
+
 --
 -- Test CREATE OR REPLACE VIEW turning a non-updatable view into an
 -- auto-updatable view and adding check options in a single step
