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 bd98dbd7ace610dee5b55819e087a75f7929a4a5..558eff7f8fdbe64444dbc2221fb9360292d321ac 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 1e6c6ef200aaa1a2089bedf680c90ad2341b2057..edb520815c5d83765727b42ccbf80117db877a96 100644 (file)
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -1527,6 +1527,13 @@ 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 b6409767f6d73feb0bd9b79ed31c22c766766da6..418589611f2afd9ca2da516dc5841595eb0aec47 100644 (file)
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -380,6 +380,9 @@ 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