[MDEV-17394] Row-based replication DATETIME(m) to DATETIME(s) does not work or incorrect Created: 2018-10-08  Updated: 2023-04-27

Status: Open
Project: MariaDB Server
Component/s: Replication
Affects Version/s: 10.0, 10.1, 10.2, 10.3, 10.4
Fix Version/s: 10.4

Type: Bug Priority: Major
Reporter: Andrei Elkin Assignee: Andrei Elkin
Resolution: Unresolved Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-17098 DATE -> DATETIME replication conversi... Closed

 Description   

When Master sets up @@global.mysql56_temporal_format=0
to create a table with DATETIME(m) column its row-based format image does not include the precision
which therefore is unknown by Slave. When master and slave precisions are different (m \not= s) both lossy and non-lossy replication fail. Consequently fails DATATIME(m) to DATE because inferred conversion involves
DATETIME(m) to DATETIME(0) at the first stage.

 Comments   
Comment by Andrei Elkin [ 2018-10-11 ]

Here is an ASAN stack as a consequence of losing the original m precision. As noted the original DATETIME(m) field arrives with zero metadata which made it to interpret as DATETIME(0). That caused incorrect unpacking and insane data led to access wrong memory addresses:

==16510==ERROR: AddressSanitizer: global-buffer-overflow on address 0x555558fc9cf9 at pc 0x555557aa5d5c bp 0x7fffdc23a530 sp 0x7fffdc23a520
 
READ of size 1 at 0x555558fc9cf9 thread T35
 
    #0 0x555557aa5d5b in check_date /home/andrei/MDB/WTs/10.2/10.2-MDEV-17098/sql-common/my_time.c:91
 
    #1 0x5555568da41e in Field_temporal_with_date::store_time_dec(st_mysql_time*, unsigned int) /home/andrei/MDB/WTs/10.2/10.2-MDEV-17098/sql/field.cc:5675
 
    #2 0x555556918f6a in Field::do_field_temporal(Copy_field*) /home/andrei/MDB/WTs/10.2/10.2-MDEV-17098/sql/field_conv.cc:434
 
    #3 0x555556916b86 in do_copy_null /home/andrei/MDB/WTs/10.2/10.2-MDEV-17098/sql/field_conv.cc:245
 
    #4 0x555556c286db in unpack_row(rpl_group_info*, TABLE*, unsigned int, unsigned char const*, st_bitmap const*, unsigned char const**, unsigned long*, unsigned char const*) /home/andrei/MDB/WTs/10.2/10.2-MDEV-17098/sql/rpl_record.cc:377
 
    #5 0x555556c25bda in Rows_log_event::unpack_current_row(rpl_group_info*) /home/andrei/MDB/WTs/10.2/10.2-MDEV-17098/sql/log_event.h:4601
 
    #6 0x555556c1a185 in Rows_log_event::write_row(rpl_group_info*, bool) /home/andrei/MDB/WTs/10.2/10.2-MDEV-17

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