Fix use-after-free bug when renaming constraints

michaelpq · michaelpq · commit 91fc2a088301 · 2018-12-17T12:43:48.000+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
@@ -2828,12 +2828,12 @@ 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 address;
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
@@ -349,7 +349,7 @@ 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
@@ -258,7 +258,7 @@ 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
`@@ -2828,12 +2828,12 @@ rename_constraint_internal(Oid myrelid,`
`2828`	`2828`
`2829`	`2829`	`if (targetrelation)`
`2830`	`2830`	`{`
`2831`		`- relation_close(targetrelation, NoLock); /* close rel but keep lock */`
`2832`		`-`
`2833`	`2831`	`/*`
`2834`	`2832`	`* Invalidate relcache so as others can see the new constraint name.`
`2835`	`2833`	`*/`
`2836`	`2834`	`CacheInvalidateRelcache(targetrelation);`
	`2835`	`+`
	`2836`	`+ relation_close(targetrelation, NoLock); /* close rel but keep lock */`
`2837`	`2837`	`}`
`2838`	`2838`
`2839`	`2839`	`return address;`