Prevent segfault in expand_tuple with no missing values

adunstan · adunstan · commit 7c44c46deb49 · 2018-04-13T16:43:33.000-04:00
Commit 16828d5 forgot to check that it had a set of missing values before trying to retrieve a value from it. An additional query to add coverage for this code is added to the regression test. Per bug report from Andreas Seltenreich.
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
@@ -981,7 +981,7 @@ expand_tuple(HeapTuple *targetHeapTuple,
 
 		Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum);
 
-		if (attrmiss[attnum].ammissingPresent)
+		if (attrmiss && attrmiss[attnum].ammissingPresent)
 		{
 			fill_val(attr,
 					 nullBits ? &nullBits : NULL,
diff --git a/src/test/regress/expected/fast_default.out b/src/test/regress/expected/fast_default.out
@@ -505,6 +505,41 @@ SELECT comp();
  Unchanged
 (1 row)
 
+-- query to exercise expand_tuple function
+CREATE TABLE t1 AS
+SELECT 1::int AS a , 2::int AS b
+FROM generate_series(1,20) q;
+ALTER TABLE t1 ADD COLUMN c text;
+SELECT a,
+       stddev(cast((SELECT sum(1) FROM generate_series(1,20) x) AS float4))
+          OVER (PARTITION BY a,b,c ORDER BY b)
+       AS z
+FROM t1;
+ a | z 
+---+---
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+ 1 | 0
+(20 rows)
+
+DROP TABLE t1;
 DROP TABLE T;
 DROP FUNCTION set(name);
 DROP FUNCTION comp();
diff --git a/src/test/regress/sql/fast_default.sql b/src/test/regress/sql/fast_default.sql
@@ -347,6 +347,20 @@ SELECT c_text FROM T WHERE c_int = -1;
 
 SELECT comp();
 
+-- query to exercise expand_tuple function
+CREATE TABLE t1 AS
+SELECT 1::int AS a , 2::int AS b
+FROM generate_series(1,20) q;
+
+ALTER TABLE t1 ADD COLUMN c text;
+
+SELECT a,
+       stddev(cast((SELECT sum(1) FROM generate_series(1,20) x) AS float4))
+          OVER (PARTITION BY a,b,c ORDER BY b)
+       AS z
+FROM t1;
+
+DROP TABLE t1;
 DROP TABLE T;
 DROP FUNCTION set(name);
 DROP FUNCTION comp();

Original file line number	Diff line number	Diff line change
`@@ -981,7 +981,7 @@ expand_tuple(HeapTuple *targetHeapTuple,`
`981`	`981`
`982`	`982`	`Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum);`
`983`	`983`
`984`		`- if (attrmiss[attnum].ammissingPresent)`
	`984`	`+ if (attrmiss && attrmiss[attnum].ammissingPresent)`
`985`	`985`	`{`
`986`	`986`	`fill_val(attr,`
`987`	`987`	`nullBits ? &nullBits : NULL,`