SIGSEGV with disabled Innodb engine

[Arty]

Hi all.

Today I met the bug in mydumper version 0.6.2, that leads to application coredump upon startup.
Here is a backtrace of the fatal:
Core was generated by `mydumper --outputdir=/backup_remote/mysql/150812 --compress --build-empty-files'.
Program terminated with signal 11, Segmentation fault.
#0 0x00007ff8e4f1f607 in ____strtoull_l_internal () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install glib2-2.40.0-4.el7.x86_64 glibc-2.17-78.0.1.el7.x86_64 keyutils-libs-1.5.8-3.el7.x86_64 krb5-libs-1.12.2-14.el7.x86_64 libcom_err-1.42.9-7.el7.x86_64 libgcc-4.8.3-9.el7.x86_64 libselinux-2.2.2-6.el7.x86_64 libstdc++-4.8.3-9.el7.x86_64 openssl-libs-1.0.1e-42.el7_1.9.x86_64 pcre-8.32-14.el7.x86_64 xz-libs-5.1.2-9alpha.el7.x86_64 zlib-1.2.7-13.el7.x86_64
(gdb) bt
#0 0x00007ff8e4f1f607 in ____strtoull_l_internal () from /lib64/libc.so.6
#1 0x000000000040586b in dump_database (conn=<optimized out>, database=0x24b1a70 "mysql") at /usr/src/debug/mydumper-0.6.2/mydumper.c:1554
#2 0x00000000004075db in start_dump (conn=0x2494470) at /usr/src/debug/mydumper-0.6.2/mydumper.c:1160
#3 0x00000000004043f2 in main (argc=1, argv=0x7ffdda67bc68) at /usr/src/debug/mydumper-0.6.2/mydumper.c:777

After some investigation I found that the bug is related to missing Innodb engine plugin, that we have forcibly disabled with 'innodb = OFF' my.cnf option (we use exclusively TokuDB and no need for InnoDB in this configuration).

The bug in dump_database() is hit when we traverse 'show table status output' and when we meet the following line ' innodb_index_stats | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Unknown storage engine 'InnoDB' |',

In this case, obviously call to g_ascii_strtoull(NULL, NULL, 10) in /usr/src/debug/mydumper-0.6.2/mydumper.c:1554

dbt->datalength = g_ascii_strtoull(row[6], NULL, 10);

makes the SIGSEGV.

So my suggestion is to check Engine or Rows for NULL values before proceeding.

Here is our 'show engine status' output example.
mysql> show table status;
+---------------------------+--------+---------+------------+------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+----------------+-----------------------------------------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment |
+---------------------------+--------+---------+------------+------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+----------------+-----------------------------------------+
| columns_priv | MyISAM | 10 | Fixed | 0 | 0 | 0 | 227994731135631359 | 4096 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_bin | NULL | | Column privileges |
| db | MyISAM | 10 | Fixed | 6 | 440 | 2640 | 123848989752688639 | 5120 | 0 | NULL | 2015-07-17 15:25:34 | 2015-08-11 18:59:41 | 2015-07-17 15:25:34 | utf8_bin | NULL | | Database privileges |
| event | MyISAM | 10 | Dynamic | 0 | 0 | 0 | 281474976710655 | 2048 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | Events |
| func | MyISAM | 10 | Fixed | 0 | 0 | 0 | 162974011515469823 | 1024 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_bin | NULL | | User defined functions |
| general_log | CSV | 10 | Dynamic | 2 | 0 | 0 | 0 | 0 | 0 | NULL | NULL | NULL | NULL | utf8_general_ci | NULL | | General log |
| help_category | MyISAM | 10 | Dynamic | 40 | 28 | 1120 | 281474976710655 | 3072 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:36 | NULL | utf8_general_ci | NULL | | help categories |
| help_keyword | MyISAM | 10 | Fixed | 485 | 197 | 95545 | 55450570411999231 | 17408 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:36 | NULL | utf8_general_ci | NULL | | help keywords |
| help_relation | MyISAM | 10 | Fixed | 1090 | 9 | 9810 | 2533274790395903 | 20480 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:36 | NULL | utf8_general_ci | NULL | | keyword-topic relation |
| help_topic | MyISAM | 10 | Dynamic | 533 | 957 | 510552 | 281474976710655 | 21504 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:36 | NULL | utf8_general_ci | NULL | | help topics |
| innodb_index_stats | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Unknown storage engine 'InnoDB' |
| innodb_table_stats | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Unknown storage engine 'InnoDB' |
| ndb_binlog_index | MyISAM | 10 | Dynamic | 0 | 0 | 0 | 281474976710655 | 1024 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | latin1_swedish_ci | NULL | | |
| plugin | MyISAM | 10 | Dynamic | 7 | 34 | 244 | 281474976710655 | 2048 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 16:07:56 | NULL | utf8_general_ci | NULL | | MySQL plugins |
| proc | MyISAM | 10 | Dynamic | 0 | 0 | 0 | 281474976710655 | 2048 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | Stored Procedures |
| procs_priv | MyISAM | 10 | Fixed | 0 | 0 | 0 | 239253730204057599 | 4096 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_bin | NULL | | Procedure privileges |
| proxies_priv | MyISAM | 10 | Fixed | 2 | 693 | 1386 | 195062158860484607 | 5120 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | utf8_bin | NULL | | User proxy privileges |
| servers | MyISAM | 10 | Fixed | 0 | 0 | 0 | 433752939111120895 | 1024 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | MySQL Foreign Servers table |
| slave_master_info | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Unknown storage engine 'InnoDB' |
| slave_relay_log_info | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Unknown storage engine 'InnoDB' |
| slave_worker_info | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Unknown storage engine 'InnoDB' |
| slow_log | CSV | 10 | Dynamic | 2 | 0 | 0 | 0 | 0 | 0 | NULL | NULL | NULL | NULL | utf8_general_ci | NULL | | Slow log |
| tables_priv | MyISAM | 10 | Fixed | 0 | 0 | 0 | 239535205180768255 | 4096 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_bin | NULL | | Table privileges |
| time_zone | MyISAM | 10 | Fixed | 0 | 0 | 0 | 1970324836974591 | 1024 | 0 | 1 | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | Time zones |
| time_zone_leap_second | MyISAM | 10 | Fixed | 0 | 0 | 0 | 3659174697238527 | 1024 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | Leap seconds information for time zones |
| time_zone_name | MyISAM | 10 | Fixed | 0 | 0 | 0 | 55450570411999231 | 1024 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | Time zone names |
| time_zone_transition | MyISAM | 10 | Fixed | 0 | 0 | 0 | 4785074604081151 | 1024 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | Time zone transitions |
| time_zone_transition_type | MyISAM | 10 | Fixed | 0 | 0 | 0 | 10696049115004927 | 1024 | 0 | NULL | 2015-07-17 15:25:34 | 2015-07-17 15:25:34 | NULL | utf8_general_ci | NULL | | Time zone transition types |
| user | MyISAM | 10 | Dynamic | 11 | 96 | 1056 | 281474976710655 | 2048 | 0 | NULL | 2015-07-17 15:25:34 | 2015-08-11 18:59:41 | NULL | utf8_bin | NULL | | Users and global privileges |
+---------------------------+--------+---------+------------+------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+----------------+-----------------------------------------+

[Arty (nopius)]

Sorry for duplicate, just checked the fixed bug list and found exactly the same report.