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 85cd47b7aecbbe40664d1e99624bd264adfaa22d..9bbad33fbdb14c1a69e554eb4d0f3bc94301e245 100644 (file)
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -111,18 +111,6 @@ 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))
        {
                /*
@@ -234,6 +222,29 @@ 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 4a16d0dbafb1d2725e2a9d3ee281a86cc252f825..f8a7dac9607d0eda385ccac217283b417eca3f0e 100644 (file)
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -1590,6 +1590,13 @@ 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 e4b7cdf703d53c188a1e78eccd3127a9d22de71e..6dae715afd8df34ac43bf5e9f867c1590b88187c 100644 (file)
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -413,6 +413,9 @@ 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