From 595220a3a3a89e5648b7b6be726502efdc9ec806 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 22 Nov 2018 15:14:01 -0500 Subject: Fix another crash in json{b}_populate_recordset and json{b}_to_recordset. populate_recordset_worker() failed to consider the possibility that the supplied JSON data contains no rows, so that update_cached_tupdesc never got called. This led to a null-pointer dereference since commit 9a5e8ed28; before that it led to a bogus "set-valued function called in context that cannot accept a set" error. Fix by forcing the update to happen. Per bug #15514. Back-patch to v11 as 9a5e8ed28 was. (If we were excited about the bogus error, we could perhaps go back further, but it'd take more work to figure out how to fix it in older branches. Given the lack of field complaints about that aspect, I'm not excited.) Discussion: https://postgr.es/m/15514-59d5b4c4065b178b@postgresql.org --- src/backend/utils/adt/jsonfuncs.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'src/backend/utils/adt/jsonfuncs.c') diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c index 06f8d281685..5c3f2fb9f6f 100644 --- a/src/backend/utils/adt/jsonfuncs.c +++ b/src/backend/utils/adt/jsonfuncs.c @@ -3658,6 +3658,12 @@ populate_recordset_worker(FunctionCallInfo fcinfo, const char *funcname, if (PG_ARGISNULL(json_arg_num)) PG_RETURN_NULL(); + /* + * Forcibly update the cached tupdesc, to ensure we have the right tupdesc + * to return even if the JSON contains no rows. + */ + update_cached_tupdesc(&cache->c.io.composite, cache->fn_mcxt); + state = palloc0(sizeof(PopulateRecordsetState)); /* make tuplestore in a sufficiently long-lived memory context */ -- cgit v1.2.3