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Make json{b}_populate_recordset() use the right tuple descriptor.

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json{b}_populate_recordset() used the tuple descriptor created from the
query-level AS clause without worrying about whether it matched the actual
input record type.  If it didn't, that would usually result in a crash,
though disclosure of server memory contents seems possible as well, for a
skilled attacker capable of issuing crafted SQL commands.  Instead, use
the query-supplied descriptor only when there is no input tuple to look at,
and otherwise get a tuple descriptor based on the input tuple's own type
marking.  The core code will detect any type mismatch in the latter case.

Michael Paquier and Tom Lane, per a report from David Rowley.
Back-patch to 9.3 where this functionality was introduced.

Security: CVE-2017-15098
This commit is contained in:
Tom Lane 2017-11-06 10:29:17 -05:00
parent b500297680
commit c0c8807ded
3 changed files with 55 additions and 21 deletions
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58
src/backend/utils/adt/jsonfuncs.c
View File

@ -1601,19 +1601,47 @@ json_populate_recordset(PG_FUNCTION_ARGS)
errmsg("set-valued function called in context that "
"cannot accept a set")));
rsi->returnMode = SFRM_Materialize;
/*
* get the tupdesc from the result set info - it must be a record type
* because we already checked that arg1 is a record type.
*/
(void) get_call_result_type(fcinfo, NULL, &tupdesc);
/* if the json is null send back an empty set */
if (PG_ARGISNULL(1))
PG_RETURN_NULL();
json = PG_GETARG_TEXT_P(1);
if (PG_ARGISNULL(0))
{
rec = NULL;
/*
* get the tupdesc from the result set info - it must be a record type
* because we already checked that arg1 is a record type
*/
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function returning record called in context "
"that cannot accept type record")));
}
else
{
rec = PG_GETARG_HEAPTUPLEHEADER(0);
/*
* use the input record's own type marking to find a tupdesc for it.
*/
tupType = HeapTupleHeaderGetTypeId(rec);
tupTypmod = HeapTupleHeaderGetTypMod(rec);
tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
}
tupType = tupdesc->tdtypeid;
tupTypmod = tupdesc->tdtypmod;
ncolumns = tupdesc->natts;
state = palloc0(sizeof(PopulateRecordsetState));
sem = palloc0(sizeof(JsonSemAction));
/* make these in a sufficiently long-lived memory context */
old_cxt = MemoryContextSwitchTo(rsi->econtext->ecxt_per_query_memory);
@ -1625,20 +1653,8 @@ json_populate_recordset(PG_FUNCTION_ARGS)
MemoryContextSwitchTo(old_cxt);
/* if the json is null send back an empty set */
if (PG_ARGISNULL(1))
PG_RETURN_NULL();
json = PG_GETARG_TEXT_P(1);
if (PG_ARGISNULL(0))
rec = NULL;
else
rec = PG_GETARG_HEAPTUPLEHEADER(0);
tupType = tupdesc->tdtypeid;
tupTypmod = tupdesc->tdtypmod;
ncolumns = tupdesc->natts;
/* unnecessary, but harmless, if tupdesc came from get_call_result_type: */
ReleaseTupleDesc(tupdesc);
lex = makeJsonLexContext(json, true);

13
src/test/regress/expected/json.out
View File

@ -907,3 +907,16 @@ select * from json_populate_recordset(row('def',99,null)::jpop,'[{"a":[100,200,3
ERROR: cannot call json_populate_recordset on a nested object
select * from json_populate_recordset(row('def',99,null)::jpop,'[{"c":[100,200,300],"x":43.2},{"a":{"z":true},"b":3,"c":"2012-01-20 10:42:53"}]') q;
ERROR: cannot call json_populate_recordset on a nested object
-- negative cases where the wrong record type is supplied
select * from json_populate_recordset(row(0::int),'[{"a":"1","b":"2"},{"a":"3"}]') q (a text, b text);
ERROR: function return row and query-specified return row do not match
DETAIL: Returned row contains 1 attribute, but query expects 2.
select * from json_populate_recordset(row(0::int,0::int),'[{"a":"1","b":"2"},{"a":"3"}]') q (a text, b text);
ERROR: function return row and query-specified return row do not match
DETAIL: Returned type integer at ordinal position 1, but query expects text.
select * from json_populate_recordset(row(0::int,0::int,0::int),'[{"a":"1","b":"2"},{"a":"3"}]') q (a text, b text);
ERROR: function return row and query-specified return row do not match
DETAIL: Returned row contains 3 attributes, but query expects 2.
select * from json_populate_recordset(row(1000000000::int,50::int),'[{"b":"2"},{"a":"3"}]') q (a text, b text);
ERROR: function return row and query-specified return row do not match
DETAIL: Returned type integer at ordinal position 1, but query expects text.

5
src/test/regress/sql/json.sql
View File

@ -302,3 +302,8 @@ select * from json_populate_recordset(row('def',99,null)::jpop,'[{"a":"blurfl","
select * from json_populate_recordset(row('def',99,null)::jpop,'[{"a":[100,200,300],"x":43.2},{"a":{"z":true},"b":3,"c":"2012-01-20 10:42:53"}]') q;
select * from json_populate_recordset(row('def',99,null)::jpop,'[{"c":[100,200,300],"x":43.2},{"a":{"z":true},"b":3,"c":"2012-01-20 10:42:53"}]') q;
-- negative cases where the wrong record type is supplied
select * from json_populate_recordset(row(0::int),'[{"a":"1","b":"2"},{"a":"3"}]') q (a text, b text);
select * from json_populate_recordset(row(0::int,0::int),'[{"a":"1","b":"2"},{"a":"3"}]') q (a text, b text);
select * from json_populate_recordset(row(0::int,0::int,0::int),'[{"a":"1","b":"2"},{"a":"3"}]') q (a text, b text);
select * from json_populate_recordset(row(1000000000::int,50::int),'[{"b":"2"},{"a":"3"}]') q (a text, b text);