BUG#38718: slave sql thread crashes when reading relay log

      
Suprisingly, a Slave_log_event would show up in the binary
log. This event is never used and should not appear in the
logs. As such, when the slave (or the mysqlbinlog tool) reads the
event, it will hit an invalid pointer (reference to the
descriptor event when deserializing the Slave_log_event was
purposodely set to NULL).
      
The presence of the Slave_log_event denotes a corrupted log, but
we cannot tell how the log got corrupted in the first
place. However, we can make the server cope with such events when
it reads them - in case of log corruption - and fail gracefully.
     
This patch makes the server/mysqlbinlog to report that it has
found an invalid log event when Slave_log_event is read.

1 files changed, 3 insertions, 1 deletions

diff --git a/sql/log_event.h b/sql/log_event.h
index 816a241e55d..662fec23639 100644
--- a/sql/log_event.h
+++ b/sql/log_event.h
@@ -1782,7 +1782,9 @@ public:
   void print(FILE* file, PRINT_EVENT_INFO* print_event_info);
 #endif
 
-  Slave_log_event(const char* buf, uint event_len);
+  Slave_log_event(const char* buf,
+                  uint event_len,
+                  const Format_description_log_event *description_event);
   ~Slave_log_event();
   int get_data_size();
   bool is_valid() const { return master_host != 0; }