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 828cd99bc1e958298bc46a9712c8de9005aacecb..90cf150d5f7a3046f518c1d0f19bc92a06336a6b 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 bec355d439122cd889573263a2ff356a8a3d2c69..3c5be773a1ad62b67b8a9e820fddeb535cc7373a 100644 (file)
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -1558,6 +1558,13 @@ 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 f8d596042ce7047fc5017279f78c10b12ac994f2..040e1bac212c334dd1aeeb1579b815ac98bf1b30 100644 (file)
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -397,6 +397,9 @@ 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