Catch stack overflow when recursing in transformFromClauseItem().

tglsfdc · tglsfdc · commit 496ab1d6c8d8 · 2022-08-13T15:21:28.000-04:00
Most parts of the parser can expect that the stack overflow check in transformExprRecurse() will trigger before things get desperate. However, transformFromClauseItem() can recurse directly to self without having analyzed any expressions, so it's possible to drive it to a stack-overrun crash. Add a check to prevent that. Per bug #17583 from Egor Chindyaskin. Back-patch to all supported branches. Richard Guo Discussion: https://postgr.es/m/17583-33be55b9f981f75c@postgresql.org
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
@@ -1054,6 +1054,9 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 						ParseNamespaceItem **top_nsitem,
 						List **namespace)
 {
+	/* Guard against stack overflow due to overly deep subtree */
+	check_stack_depth();
+
 	if (IsA(n, RangeVar))
 	{
 		/* Plain relation reference, or perhaps a CTE reference */

Original file line number	Diff line number	Diff line change
`@@ -1054,6 +1054,9 @@ transformFromClauseItem(ParseState pstate, Node n,`
`1054`	`1054`	`ParseNamespaceItem **top_nsitem,`
`1055`	`1055`	`List **namespace)`
`1056`	`1056`	`{`
	`1057`	`+ /* Guard against stack overflow due to overly deep subtree */`
	`1058`	`+ check_stack_depth();`
	`1059`	`+`
`1057`	`1060`	`if (IsA(n, RangeVar))`
`1058`	`1061`	`{`
`1059`	`1062`	`/* Plain relation reference, or perhaps a CTE reference */`