v1-0001-Fix-Assert-failure-in-XMLTABLE-parser.patch

From 312ea93bfac03db7b1e5e72e173f272851ca57d0 Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Tue, 13 May 2025 17:56:55 +0900
Subject: [PATCH v1] Fix Assert failure in XMLTABLE parser

In an XMLTABLE expression, columns can be marked NOT NULL, and the
parser internally fabricates an option named "is_not_null" to
represent this.  However, the parser also allows users to specify
arbitrary option names.  This creates a conflict: a user can
explicitly use "is_not_null" as an option name and assign it a
non-Boolean value, which violates internal assumptions and triggers an
assertion failure.

To fix, this patch checks whether a user-supplied name collides with
the internally reserved option name and raises an error if so.
Additionally, the internal name is renamed to "__pg__is_not_null" to
further reduce the risk of collision with user-defined names.
---
 src/backend/parser/gram.y           | 15 +++++++++++----
 src/test/regress/expected/xml.out   |  4 ++++
 src/test/regress/expected/xml_1.out |  4 ++++
 src/test/regress/expected/xml_2.out |  4 ++++
 src/test/regress/sql/xml.sql        |  2 ++
 5 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 3c4268b271a..0b5652071d1 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -14230,7 +14230,7 @@ xmltable_column_el:
 										 parser_errposition(defel->location)));
 							fc->colexpr = defel->arg;
 						}
-						else if (strcmp(defel->defname, "is_not_null") == 0)
+						else if (strcmp(defel->defname, "__pg__is_not_null") == 0)
 						{
 							if (nullability_seen)
 								ereport(ERROR,
@@ -14273,13 +14273,20 @@ xmltable_column_option_list:
 
 xmltable_column_option_el:
 			IDENT b_expr
-				{ $$ = makeDefElem($1, $2, @1); }
+				{
+					if (strcmp($1, "__pg__is_not_null") == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("option name \"%s\" cannot be used in XMLTABLE", $1),
+								 parser_errposition(@1)));
+					$$ = makeDefElem($1, $2, @1);
+				}
 			| DEFAULT b_expr
 				{ $$ = makeDefElem("default", $2, @1); }
 			| NOT NULL_P
-				{ $$ = makeDefElem("is_not_null", (Node *) makeBoolean(true), @1); }
+				{ $$ = makeDefElem("__pg__is_not_null", (Node *) makeBoolean(true), @1); }
 			| NULL_P
-				{ $$ = makeDefElem("is_not_null", (Node *) makeBoolean(false), @1); }
+				{ $$ = makeDefElem("__pg__is_not_null", (Node *) makeBoolean(false), @1); }
 			| PATH b_expr
 				{ $$ = makeDefElem("path", $2, @1); }
 		;
diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out
index bcc743f4851..103a22a3b1d 100644
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -1373,6 +1373,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 ERROR:  XMLTABLE function has 1 columns available but 2 columns specified
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+ERROR:  option name "__pg__is_not_null" cannot be used in XMLTABLE
+LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
+                                                             ^
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'
diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out
index a1c5d314171..73c411118a3 100644
--- a/src/test/regress/expected/xml_1.out
+++ b/src/test/regress/expected/xml_1.out
@@ -1047,6 +1047,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 ERROR:  XMLTABLE function has 1 columns available but 2 columns specified
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+ERROR:  option name "__pg__is_not_null" cannot be used in XMLTABLE
+LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
+                                                             ^
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'
diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out
index 045641dae64..a85d95358d9 100644
--- a/src/test/regress/expected/xml_2.out
+++ b/src/test/regress/expected/xml_2.out
@@ -1359,6 +1359,10 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 ERROR:  XMLTABLE function has 1 columns available but 2 columns specified
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+ERROR:  option name "__pg__is_not_null" cannot be used in XMLTABLE
+LINE 1: ...MLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_n...
+                                                             ^
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'
diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql
index 4c3520ce898..0ea4f508837 100644
--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -435,6 +435,8 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 -- errors
 SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
 
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp __pg__is_not_null 1) AS f (v1);
+
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'
-- 
2.43.0