Re: BUG #17561: Server crashes on executing row() with very long argument list

I wrote:
> I think the parser should've prevented this.  It's in charge of
> rejecting overlength SELECT lists, for example.  Also, the limit
> probably needs to be just MaxTupleAttributeNumber.

Concretely, about as attached.

In the existing code, if you just supply 10000 or so columns you
reach this error in heaptuple.c:

    if (numberOfAttributes > MaxTupleAttributeNumber)
        ereport(ERROR,
                (errcode(ERRCODE_TOO_MANY_COLUMNS),
                 errmsg("number of columns (%d) exceeds limit (%d)",
                        numberOfAttributes, MaxTupleAttributeNumber)));

I borrowed the errcode from that, but the wording from parse_node.c:

    if (pstate->p_next_resno - 1 > MaxTupleAttributeNumber)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("target lists can have at most %d entries",
                        MaxTupleAttributeNumber)));

I'm a bit inclined to adjust parse_node.c to also use TOO_MANY_COLUMNS
(54011) instead of the generic PROGRAM_LIMIT_EXCEEDED (54000).

            regards, tom lane

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 9f567f4bf4..059cb7097c 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -2140,6 +2140,14 @@ transformRowExpr(ParseState *pstate, RowExpr *r, bool allowDefault)
     newr->args = transformExpressionList(pstate, r->args,
                                          pstate->p_expr_kind, allowDefault);

+    /* Disallow more columns than will fit in a tuple */
+    if (list_length(newr->args) > MaxTupleAttributeNumber)
+        ereport(ERROR,
+                (errcode(ERRCODE_TOO_MANY_COLUMNS),
+                 errmsg("ROW expressions can have at most %d entries",
+                        MaxTupleAttributeNumber),
+                 parser_errposition(pstate, r->location)));
+
     /* Barring later casting, we consider the type RECORD */
     newr->row_typeid = RECORDOID;
     newr->row_format = COERCE_IMPLICIT_CAST;