MDEV-29473 UBSAN: Signed integer overflow: X * Y cannot be represented in type 'int' in strings/dtoa.c

Fixing a few problems relealed by UBSAN in type_float.test

- multiplication overflow in dtoa.c

- uninitialized Field::geom_type (and Field::srid as well)

- Wrong call-back function types used in combination with SHOW_FUNC.
  Changes in the mysql_show_var_func data type definition were not
  properly addressed all around the code by the following commits:
    b4ff64568c88ab3ce559e7bd39853d9cbf86704a
    18feb62feeb833494d003615861b9c78ec008a90
    0ee879ff8ac1b80cd9a963015344f5698a81f309

  Adding a helper SHOW_FUNC_ENTRY() function and replacing
  all mysql_show_var_func declarations using SHOW_FUNC
  to SHOW_FUNC_ENTRY, to catch mysql_show_var_func in the future
  at compilation time.

3 files changed, 18 insertions, 14 deletions

diff --git a/sql/field.cc b/sql/field.cc
index f430e6209d5..43514347106 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -11073,6 +11073,8 @@ bool Field_vers_trx_id::test_if_equality_guarantees_uniqueness(const Item* item)
 Column_definition::Column_definition(THD *thd, Field *old_field,
                                                Field *orig_field)
 {
+  geom_type= Field::GEOM_GEOMETRY;
+  srid= 0;
   on_update=  NULL;
   field_name= old_field->field_name;
   length=     old_field->field_length;
diff --git a/sql/log.cc b/sql/log.cc
index 7ca9b38dc6e..4b071f133f7 100644
--- a/sql/log.cc
+++ b/sql/log.cc
@@ -10501,7 +10501,7 @@ static int show_binlog_vars(THD *thd, SHOW_VAR *var, void *,
 }
 
 static SHOW_VAR binlog_status_vars_top[]= {
-  {"Binlog", (char *) &show_binlog_vars, SHOW_FUNC},
+  SHOW_FUNC_ENTRY("Binlog", &show_binlog_vars),
   {NullS, NullS, SHOW_LONG}
 };
 
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index 84c3b9fb0a6..d58f2ed557f 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -8395,7 +8395,9 @@ static int show_ssl_get_cipher_list(THD *thd, SHOW_VAR *var, char *buff,
     rpl_semi_sync_master_show_##name
 
 #define DEF_SHOW_FUNC(name, show_type)                                       \
-    static  int SHOW_FNAME(name)(MYSQL_THD thd, SHOW_VAR *var, char *buff)   \
+    static  int SHOW_FNAME(name)(MYSQL_THD thd, SHOW_VAR *var, void *buff,   \
+                                 system_status_var *status_var,              \
+                                 enum_var_type var_type)                     \
     {                                                                        \
       repl_semisync_master.set_export_stats();                                 \
       var->type= show_type;                                                  \
@@ -8661,7 +8663,7 @@ SHOW_VAR status_vars[]= {
   {"Created_tmp_files",	       (char*) &my_tmp_file_created,	SHOW_LONG},
   {"Created_tmp_tables",       (char*) offsetof(STATUS_VAR, created_tmp_tables_), SHOW_LONG_STATUS},
 #ifndef DBUG_OFF
-  {"Debug",                    (char*) &debug_status_func,  SHOW_FUNC},
+  SHOW_FUNC_ENTRY("Debug",     &debug_status_func),
 #endif
   {"Delayed_errors",           (char*) &delayed_insert_errors,  SHOW_LONG},
   {"Delayed_insert_threads",   (char*) &delayed_insert_threads, SHOW_LONG_NOFLUSH},
@@ -8713,7 +8715,7 @@ SHOW_VAR status_vars[]= {
   {"Handler_tmp_write",        (char*) offsetof(STATUS_VAR, ha_tmp_write_count), SHOW_LONG_STATUS},
   {"Handler_update",           (char*) offsetof(STATUS_VAR, ha_update_count), SHOW_LONG_STATUS},
   {"Handler_write",            (char*) offsetof(STATUS_VAR, ha_write_count), SHOW_LONG_STATUS},
-  {"Key",                      (char*) &show_default_keycache, SHOW_FUNC},
+  SHOW_FUNC_ENTRY("Key",       &show_default_keycache),
   {"Last_query_cost",          (char*) offsetof(STATUS_VAR, last_query_cost), SHOW_DOUBLE_STATUS},
   {"Max_statement_time_exceeded", (char*) offsetof(STATUS_VAR, max_statement_time_exceeded), SHOW_LONG_STATUS},
   {"Master_gtid_wait_count",   (char*) offsetof(STATUS_VAR, master_gtid_wait_count), SHOW_LONG_STATUS},
@@ -8737,20 +8739,20 @@ SHOW_VAR status_vars[]= {
   {"Rows_read",                (char*) offsetof(STATUS_VAR, rows_read), SHOW_LONGLONG_STATUS},
   {"Rows_tmp_read",            (char*) offsetof(STATUS_VAR, rows_tmp_read), SHOW_LONGLONG_STATUS},
 #ifdef HAVE_REPLICATION
-  {"Rpl_semi_sync_master_status", (char*) &SHOW_FNAME(status), SHOW_FUNC},
-  {"Rpl_semi_sync_master_clients", (char*) &SHOW_FNAME(clients), SHOW_FUNC},
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_status", &SHOW_FNAME(status)),
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_clients", &SHOW_FNAME(clients)),
   {"Rpl_semi_sync_master_yes_tx", (char*) &rpl_semi_sync_master_yes_transactions, SHOW_LONG},
   {"Rpl_semi_sync_master_no_tx", (char*) &rpl_semi_sync_master_no_transactions, SHOW_LONG},
-  {"Rpl_semi_sync_master_wait_sessions", (char*) &SHOW_FNAME(wait_sessions), SHOW_FUNC},
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_wait_sessions", &SHOW_FNAME(wait_sessions)),
   {"Rpl_semi_sync_master_no_times", (char*) &rpl_semi_sync_master_off_times, SHOW_LONG},
   {"Rpl_semi_sync_master_timefunc_failures", (char*) &rpl_semi_sync_master_timefunc_fails, SHOW_LONG},
   {"Rpl_semi_sync_master_wait_pos_backtraverse", (char*) &rpl_semi_sync_master_wait_pos_backtraverse, SHOW_LONG},
-  {"Rpl_semi_sync_master_tx_wait_time", (char*) &SHOW_FNAME(trx_wait_time), SHOW_FUNC},
-  {"Rpl_semi_sync_master_tx_waits", (char*) &SHOW_FNAME(trx_wait_num), SHOW_FUNC},
-  {"Rpl_semi_sync_master_tx_avg_wait_time", (char*) &SHOW_FNAME(avg_trx_wait_time), SHOW_FUNC},
-  {"Rpl_semi_sync_master_net_wait_time", (char*) &SHOW_FNAME(net_wait_time), SHOW_FUNC},
-  {"Rpl_semi_sync_master_net_waits", (char*) &SHOW_FNAME(net_wait_num), SHOW_FUNC},
-  {"Rpl_semi_sync_master_net_avg_wait_time", (char*) &SHOW_FNAME(avg_net_wait_time), SHOW_FUNC},
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_tx_wait_time", &SHOW_FNAME(trx_wait_time)),
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_tx_waits", &SHOW_FNAME(trx_wait_num)),
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_tx_avg_wait_time", &SHOW_FNAME(avg_trx_wait_time)),
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_net_wait_time", &SHOW_FNAME(net_wait_time)),
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_net_waits", &SHOW_FNAME(net_wait_num)),
+  SHOW_FUNC_ENTRY("Rpl_semi_sync_master_net_avg_wait_time", &SHOW_FNAME(avg_net_wait_time)),
   {"Rpl_semi_sync_master_request_ack", (char*) &rpl_semi_sync_master_request_ack, SHOW_LONGLONG},
   {"Rpl_semi_sync_master_get_ack", (char*)&rpl_semi_sync_master_get_ack, SHOW_LONGLONG},
   {"Rpl_semi_sync_slave_status", (char*) &rpl_semi_sync_slave_status, SHOW_BOOL},
@@ -8858,7 +8860,7 @@ SHOW_VAR status_vars[]= {
   {"Uptime_since_flush_status",(char*) &show_flushstatustime,   SHOW_SIMPLE_FUNC},
 #endif
 #ifdef WITH_WSREP
-  {"wsrep",                    (char*) &wsrep_show_status,       SHOW_FUNC},
+  SHOW_FUNC_ENTRY("wsrep",     &wsrep_show_status),
 #endif
   {NullS, NullS, SHOW_LONG}
 };