In transformRowExpr(), check for too many columns in the row.

A RowExpr with more than MaxTupleAttributeNumber columns would fail at
execution anyway, since we cannot form a tuple datum with more than that
many columns.  While heap_form_tuple() has a check for too many columns,
it emerges that there are some intermediate bits of code that don't
check and can be driven to failure with sufficiently many columns.
Checking this at parse time seems like the most appropriate place to
install a defense, since we already check SELECT list length there.

While at it, make the SELECT-list-length error use the same errcode
(TOO_MANY_COLUMNS) as heap_form_tuple does, rather than the generic
PROGRAM_LIMIT_EXCEEDED.

Per bug #17561 from Egor Chindyaskin.  The given test case crashes
in all supported branches (and probably a lot further back),
so patch all.

Discussion: https://postgr.es/m/17561-80350151b9ad2ad4@postgresql.org

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 197c432dd419b302430cbaee7973d9516e9eff92..d30fc1301c8715b9f519b93a708fbc0f14814675 100644 (file)
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -15,6 +15,7 @@
 
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "catalog/pg_type.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
@@ -2176,6 +2177,14 @@ 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;

diff --git a/src/backend/parser/parse_node.c b/src/backend/parser/parse_node.c
index 6dbad53a41017f82e9007d0e6fd6c707c1cd35c6..25a3edb8243f7082eb1661db8f28f3cc540ab3e2 100644 (file)
--- a/src/backend/parser/parse_node.c
+++ b/src/backend/parser/parse_node.c
@@ -83,7 +83,7 @@ free_parsestate(ParseState *pstate)
     */
    if (pstate->p_next_resno - 1 > MaxTupleAttributeNumber)
        ereport(ERROR,
-               (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+               (errcode(ERRCODE_TOO_MANY_COLUMNS),
                 errmsg("target lists can have at most %d entries",
                        MaxTupleAttributeNumber)));