Catch stack overflow when recursing in transformFromClauseItem().

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
index 2763af9470e0cca1414897e2491d6634a2f5fa97..b5a984ad14bcf88def205e5390898e865dc3a716 100644 (file)
--- 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 */