0001-Fix-segmentation-fault-in-MergeInheritedAtt-20240430.patch

From 7c1ff7b17933eef9523486a2c0a054836db9cf24 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Date: Tue, 30 Apr 2024 11:19:43 +0530
Subject: [PATCH] Fix segmentation fault in MergeInheritedAttribute()

While converting a pg_attribute tuple into a ColumnDef, ColumnDef::compression
remains NULL if there is no compression method set fot the attribute. Calling
strcmp() with NULL ColumnDef::compression, when comparing compression methods
of parents, causes segmentation fault in MergeInheritedAttribute(). Skip
comparing compression methods if either of them is NULL.

Author: Ashutosh Bapat
Discussion: https://www.postgresql.org/message-id/b22a6834-aacb-7b18-0424-a3f5fe889667%40gmail.com
---
 src/backend/commands/tablecmds.c          | 16 ++++++++++------
 src/test/regress/expected/compression.out | 10 +++++++---
 src/test/regress/sql/compression.sql      |  8 +++++---
 3 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 3556240c8e..e29f96e357 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -3430,12 +3430,16 @@ MergeInheritedAttribute(List *inh_columns,
 	 */
 	if (prevdef->compression == NULL)
 		prevdef->compression = newdef->compression;
-	else if (strcmp(prevdef->compression, newdef->compression) != 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_DATATYPE_MISMATCH),
-				 errmsg("column \"%s\" has a compression method conflict",
-						attributeName),
-				 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
+	else if (newdef->compression != NULL)
+	{
+		if (strcmp(prevdef->compression, newdef->compression) != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("column \"%s\" has a compression method conflict",
+							attributeName),
+					 errdetail("%s versus %s",
+							   prevdef->compression, newdef->compression)));
+	}
 
 	/*
 	 * Check for GENERATED conflicts
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 834b7555cb..4dd9ee7200 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -223,15 +223,18 @@ SELECT pg_column_compression(f1) FROM cmpart2;
  pglz
 (1 row)
 
--- test compression with inheritance, error
-CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
+-- test compression with inheritance
+CREATE TABLE cminh() INHERITS(cmdata, cmdata1); -- error
 NOTICE:  merging multiple inherited definitions of column "f1"
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
-CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
+CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata); -- error
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+CREATE TABLE cmdata3(f1 text);
+CREATE TABLE cminh() INHERITS (cmdata, cmdata3);
+NOTICE:  merging multiple inherited definitions of column "f1"
 -- test default_toast_compression GUC
 SET default_toast_compression = '';
 ERROR:  invalid value for parameter "default_toast_compression": ""
@@ -251,6 +254,7 @@ INSERT INTO cmdata VALUES (repeat('123456789', 4004));
  f1     | text |           |          |         | extended | lz4         |              | 
 Indexes:
     "idx" btree (f1)
+Child tables: cminh
 
 SELECT pg_column_compression(f1) FROM cmdata;
  pg_column_compression 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 7179a5002e..490595fcfb 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -93,9 +93,11 @@ INSERT INTO cmpart VALUES (repeat('123456789', 4004));
 SELECT pg_column_compression(f1) FROM cmpart1;
 SELECT pg_column_compression(f1) FROM cmpart2;
 
--- test compression with inheritance, error
-CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
-CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
+-- test compression with inheritance
+CREATE TABLE cminh() INHERITS(cmdata, cmdata1); -- error
+CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata); -- error
+CREATE TABLE cmdata3(f1 text);
+CREATE TABLE cminh() INHERITS (cmdata, cmdata3);
 
 -- test default_toast_compression GUC
 SET default_toast_compression = '';
-- 
2.34.1