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 8ebee4fa5f38703f34ab311911895c26a312bd6e..6322deeb122766b817a4124f8cf8397a4c3d8eda 100644 (file)
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -1099,6 +1099,9 @@ transformFromClauseItem(ParseState *pstate, Node *n,
                        RangeTblEntry **top_rte, int *top_rti,
                        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 */