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 ece4dd03296e7a103602e375724a92ba4c6a0510..fab9d0d293d2fc356f4cc0cfc1ccf72a41b4c60c 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 f4fe030a39aa97888517fa5f3919e039cebe4a96..f6530e5b0ceb008ff93bc3633ac4b71c198527a9 100644 (file)
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -1565,6 +1565,13 @@ 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 141d4c72765eced7a3c08744d5b9507e5d487153..66d731a3fd3c5180cfbba4d67ea81f481fe26bb3 100644 (file)
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -407,6 +407,9 @@ 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