MDEV-20311 row_ins_step accesses unitialized memory

ins_node_create() does not initialize all members of que_common_t, so
zero-init them with mem_heap_zalloc().

Handle out-of-memory correctly.

Init insert_node->common.parent to fulfill the contract of thr usage.

Free insert_node subtree at row_update_vers_insert() exit.

storage/innobase/row/row0ins.cc

@@ -74,20 +74,18 @@ ins_node_create(
 	ins_node_t*	node;
 
 	node = static_cast<ins_node_t*>(
-		mem_heap_alloc(heap, sizeof(ins_node_t)));
+		mem_heap_zalloc(heap, sizeof(ins_node_t)));
+
+	if (!node) {
+		return(NULL);
+	}
 
 	node->common.type = QUE_NODE_INSERT;
 
 	node->ins_type = ins_type;
 
 	node->state = INS_NODE_SET_IX_LOCK;
 	node->table = table;
-	node->index = NULL;
-	node->entry = NULL;
-
-	node->select = NULL;
-
-	node->trx_id = 0;
 
 	node->entry_sys_heap = mem_heap_create(128);
 

storage/innobase/row/row0mysql.cc

@@ -2150,7 +2150,9 @@ This is used in UPDATE CASCADE/SET NULL of a system versioning table.
 @return DB_SUCCESS or some error */
 static dberr_t row_update_vers_insert(que_thr_t* thr, upd_node_t* node)
 {
-	const trx_t* trx = thr_get_trx(thr);
+	trx_t* trx = thr_get_trx(thr);
+	dfield_t* row_end;
+	char row_end_data[8];
 	dict_table_t* table = node->table;
 	ut_ad(table->versioned());
 
@@ -2161,10 +2163,15 @@ static dberr_t row_update_vers_insert(que_thr_t* thr, upd_node_t* node)
 	ins_node_t* insert_node =
 		ins_node_create(INS_DIRECT, table, node->historical_heap);
 
+	if (!insert_node) {
+		trx->error_state = DB_OUT_OF_MEMORY;
+		goto exit;
+	}
+
+	insert_node->common.parent = thr;
 	ins_node_set_new_row(insert_node, row);
 
-	dfield_t* row_end = dtuple_get_nth_field(row, table->vers_end);
-	char row_end_data[8];
+	row_end = dtuple_get_nth_field(row, table->vers_end);
 	if (dict_table_get_nth_col(table, table->vers_end)->vers_native()) {
 		mach_write_to_8(row_end_data, trx->id);
 		dfield_set_data(row_end, row_end_data, 8);
@@ -2202,6 +2209,7 @@ static dberr_t row_update_vers_insert(que_thr_t* thr, upd_node_t* node)
 		}
 	}
 exit:
+	que_graph_free_recursive(insert_node);
 	mem_heap_free(node->historical_heap);
 	node->historical_heap = NULL;
 	return trx->error_state;