MDEV-21490: binlog tests fail with valgrind: Conditional jump or move depends on uninitialised value in sql_ex_info::init

Problem:
=======
P1) Conditional jump or move depends on uninitialised value(s)
    sql_ex_info::init(char const*, char const*, bool) (log_event.cc:3083)

code: All the following variables are not initialized.
----
  return ((cached_new_format != -1) ? cached_new_format :
    (cached_new_format=(field_term_len > 1 || enclosed_len > 1 ||
    line_term_len > 1 || line_start_len > 1 || escaped_len > 1)));

P2) Conditional jump or move depends on uninitialised value(s)
    Rows_log_event::Rows_log_event(char const*, unsigned
      int, Format_description_log_event const*) (log_event.cc:9571)

Code: Uninitialized values is reported for 'var_header_len' variable.
----
  if (var_header_len < 2 || event_len < static_cast<unsigned
      int>(var_header_len + (post_start - buf)))

P3) Conditional jump or move depends on uninitialised value(s)
    Table_map_log_event::pack_info(Protocol*) (log_event.cc:11553)

code:'m_table_id' is uninitialized.
----
  void Table_map_log_event::pack_info(Protocol *protocol)
  ...
  size_t bytes= my_snprintf(buf, sizeof(buf), "table_id: %lu (%s.%s)",
                              m_table_id, m_dbnam, m_tblnam);

Fix:
===
P1 - Fix)
Initialize cached_new_format,field_term_len, enclosed_len, line_term_len,
line_start_len, escaped_len members in default constructor.

P2 - Fix)
"var_header_len" is initialized by reading the event buffer. In case of an
invalid event the buffer will contain invalid data. Hence added a check to
validate the event data. If event_len is smaller than valid header length
return immediately.

P3 - Fix)
'm_table_id' within Table_map_log_event is initialized by reading data from
the event buffer. Use 'VALIDATE_BYTES_READ' macro to validate the current
state of the buffer. If it is invalid return immediately.

2 files changed, 17 insertions, 2 deletions

diff --git a/sql/log_event.cc b/sql/log_event.cc
index e8881c77f2b..d731c39d9c5 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -5902,7 +5902,7 @@ int Load_log_event::copy_log_event(const char *buf, ulong event_len,
 {
   DBUG_ENTER("Load_log_event::copy_log_event");
   uint data_len;
-  if ((int) event_len < body_offset)
+  if ((int) event_len <= body_offset)
     DBUG_RETURN(1);
   char* buf_end = (char*)buf + event_len;
   /* this is the beginning of the post-header */
@@ -9535,6 +9535,12 @@ Rows_log_event::Rows_log_event(const char *buf, uint event_len,
 
   uint8 const post_header_len= description_event->post_header_len[event_type-1];
 
+  if (event_len < (uint)(common_header_len + post_header_len))
+  {
+    m_cols.bitmap= 0;
+    DBUG_VOID_RETURN;
+  }
+
   DBUG_PRINT("enter",("event_len: %u  common_header_len: %d  "
 		      "post_header_len: %d",
 		      event_len, common_header_len,
@@ -11043,6 +11049,7 @@ Table_map_log_event::Table_map_log_event(const char *buf, uint event_len,
   const char *post_start= buf + common_header_len;
 
   post_start+= TM_MAPID_OFFSET;
+  VALIDATE_BYTES_READ(post_start, buf, event_len);
   if (post_header_len == 6)
   {
     /* Master is of an intermediate source tree before 5.1.4. Id is 4 bytes */
diff --git a/sql/log_event.h b/sql/log_event.h
index 2c8dc3d7353..1337e9a7d69 100644
--- a/sql/log_event.h
+++ b/sql/log_event.h
@@ -2057,7 +2057,15 @@ public:        /* !!! Public in this patch to allow old usage */
  ****************************************************************************/
 struct sql_ex_info
 {
-  sql_ex_info() {}                            /* Remove gcc warning */
+  sql_ex_info():
+    cached_new_format(-1),
+    field_term_len(0),
+    enclosed_len(0),
+    line_term_len(0),
+    line_start_len(0),
+    escaped_len(0),
+    empty_flags(0)
+  {}                            /* Remove gcc warning */
   const char* field_term;
   const char* enclosed;
   const char* line_term;