Compute aggregate argument types correctly in transformAggregateCall().

transformAggregateCall() captures the datatypes of the aggregate's
arguments immediately to construct the Aggref.aggargtypes list.
This seems reasonable because the arguments have already been
transformed --- but there is an edge case where they haven't been.
Specifically, if we have an unknown-type literal in an ANY argument
position, nothing will have been done with it earlier.  But if we
also have DISTINCT, then addTargetToGroupList() converts the literal
to "text" type, resulting in the aggargtypes list not matching the
actual runtime type of the argument.  The end result is that the
aggregate tries to interpret a "text" value as being of type
"unknown", that is a zero-terminated C string.  If the text value
contains no zero bytes, this could result in disclosure of server
memory following the text literal value.

To fix, move the collection of the aggargtypes list to the end
of transformAggregateCall(), after DISTINCT has been handled.
This requires slightly more code, but not a great deal.

Our thanks to Jingzhou Fu for reporting this problem.

Security: CVE-2023-5868

diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 430ed9cf37c1d2d600990a5ab11630c182892db4..f490fd032a880803a4881516cc7923f34a98a516 100644 (file)
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -110,18 +110,6 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
        int                     save_next_resno;
        ListCell   *lc;
 
-       /*
-        * Before separating the args into direct and aggregated args, make a list
-        * of their data type OIDs for use later.
-        */
-       foreach(lc, args)
-       {
-               Expr       *arg = (Expr *) lfirst(lc);
-
-               argtypes = lappend_oid(argtypes, exprType((Node *) arg));
-       }
-       agg->aggargtypes = argtypes;
-
        if (AGGKIND_IS_ORDERED_SET(agg->aggkind))
        {
                /*
@@ -233,6 +221,29 @@ transformAggregateCall(ParseState *pstate, Aggref *agg,
        agg->aggorder = torder;
        agg->aggdistinct = tdistinct;
 
+       /*
+        * Now build the aggargtypes list with the type OIDs of the direct and
+        * aggregated args, ignoring any resjunk entries that might have been
+        * added by ORDER BY/DISTINCT processing.  We can't do this earlier
+        * because said processing can modify some args' data types, in particular
+        * by resolving previously-unresolved "unknown" literals.
+        */
+       foreach(lc, agg->aggdirectargs)
+       {
+               Expr       *arg = (Expr *) lfirst(lc);
+
+               argtypes = lappend_oid(argtypes, exprType((Node *) arg));
+       }
+       foreach(lc, tlist)
+       {
+               TargetEntry *tle = (TargetEntry *) lfirst(lc);
+
+               if (tle->resjunk)
+                       continue;                       /* ignore junk */
+               argtypes = lappend_oid(argtypes, exprType((Node *) tle->expr));
+       }
+       agg->aggargtypes = argtypes;
+
        check_agglevels_and_constraints(pstate, (Node *) agg);
 }
 

diff --git a/src/test/regress/expected/jsonb.out b/src/test/regress/expected/jsonb.out
index f0388190ef4c5c8db3a5ba0519c86e71d2c360c0..7ae92e94a6bd3ac95c3b910b356a707d777d0e4d 100644 (file)
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -1523,6 +1523,13 @@ SELECT jsonb_object_agg(name, type) FROM foo;
 INSERT INTO foo VALUES (999999, NULL, 'bar');
 SELECT jsonb_object_agg(name, type) FROM foo;
 ERROR:  field name must not be null
+-- edge case for parser
+SELECT jsonb_object_agg(DISTINCT 'a', 'abc');
+ jsonb_object_agg 
+------------------
+ {"a": "abc"}
+(1 row)
+
 -- jsonb_object
 -- empty object, one dimension
 SELECT jsonb_object('{}');

diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql
index d67d191c8866c7af3f438ed62c6132d8055b1a16..17a9e9a48b16018c950ead05277105edaf15470c 100644 (file)
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -376,6 +376,9 @@ SELECT jsonb_object_agg(name, type) FROM foo;
 INSERT INTO foo VALUES (999999, NULL, 'bar');
 SELECT jsonb_object_agg(name, type) FROM foo;
 
+-- edge case for parser
+SELECT jsonb_object_agg(DISTINCT 'a', 'abc');
+
 -- jsonb_object
 
 -- empty object, one dimension