Fix use-after-free bug when renaming constraints

michaelpq · michaelpq · commit 696c68c2be44 · 2018-12-17T12:44:09.000+09:00
This is an oversight from recent commit b13fd34. While on it, tweak the previous test with a better name for the renamed primary key. Detected by buildfarm member prion which forces relation cache release with -DRELCACHE_FORCE_RELEASE. Back-patch down to 9.4 as the previous commit.
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
@@ -2429,12 +2429,12 @@ rename_constraint_internal(Oid myrelid,
 
 	if (targetrelation)
 	{
-		relation_close(targetrelation, NoLock); /* close rel but keep lock */
-
 		/*
 		 * Invalidate relcache so as others can see the new constraint name.
 		 */
 		CacheInvalidateRelcache(targetrelation);
+
+		relation_close(targetrelation, NoLock); /* close rel but keep lock */
 	}
 
 	return constraintOid;
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
@@ -347,7 +347,7 @@ CREATE TABLE constraint_rename_cache (a int,
 ALTER TABLE constraint_rename_cache
   RENAME CONSTRAINT chk_a TO chk_a_new;
 ALTER TABLE constraint_rename_cache
-  RENAME CONSTRAINT constraint_rename_cache_pkey TO chk_a_gt_zero;
+  RENAME CONSTRAINT constraint_rename_cache_pkey TO constraint_rename_pkey_new;
 CREATE TABLE like_constraint_rename_cache
   (LIKE constraint_rename_cache INCLUDING ALL);
 \d like_constraint_rename_cache
diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
@@ -257,7 +257,7 @@ CREATE TABLE constraint_rename_cache (a int,
 ALTER TABLE constraint_rename_cache
   RENAME CONSTRAINT chk_a TO chk_a_new;
 ALTER TABLE constraint_rename_cache
-  RENAME CONSTRAINT constraint_rename_cache_pkey TO chk_a_gt_zero;
+  RENAME CONSTRAINT constraint_rename_cache_pkey TO constraint_rename_pkey_new;
 CREATE TABLE like_constraint_rename_cache
   (LIKE constraint_rename_cache INCLUDING ALL);
 \d like_constraint_rename_cache

Original file line number	Diff line number	Diff line change
`@@ -2429,12 +2429,12 @@ rename_constraint_internal(Oid myrelid,`
`2429`	`2429`
`2430`	`2430`	`if (targetrelation)`
`2431`	`2431`	`{`
`2432`		`- relation_close(targetrelation, NoLock); /* close rel but keep lock */`
`2433`		`-`
`2434`	`2432`	`/*`
`2435`	`2433`	`* Invalidate relcache so as others can see the new constraint name.`
`2436`	`2434`	`*/`
`2437`	`2435`	`CacheInvalidateRelcache(targetrelation);`
	`2436`	`+`
	`2437`	`+ relation_close(targetrelation, NoLock); /* close rel but keep lock */`
`2438`	`2438`	`}`
`2439`	`2439`
`2440`	`2440`	`return constraintOid;`