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  1. MariaDB Server
  2. MDEV-6091

mysqldump goes in a loop and segfaults if --dump-slave is specified and it cannot connect to the server

Details

    Description

      To reproduce the bug, launch a mysqldump with the --dump-slave option on a server it cannot connect or execute a "SHOW SLAVE STATUS" :

      # mysqldump -hunknownhost --dump-slave nulldb
      mysqldump: Got error: 2005: "Unknown MySQL server host 'unknownhost' (0)" when trying to connect
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      [...]
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      mysqldump: Couldn't execute 'SHOW SLAVE STATUS': MySQL server has gone away (2006)
      Segmentation fault

      Expected result: It shouldnt try to execute the "SHOW SLAVE STATUS" query as it cannot connect to the server and definitely not go on a loop and segfault.

      –
      Note: The bug might have appeared since MDEV-5624 has been fixed, i don't recall seeing that issue before 5.5.36 but I might be wrong about that.

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          The error is the typo:

          err:
            /* if --dump-slave , start the slave sql thread */
            if (opt_slave_data && do_start_slave_sql(mysql))
              goto err;

          But I don't know what was meant to be done under if, so I'll leave it to serg to fix as initially intended.

          elenst Elena Stepanova added a comment - The error is the typo: err: /* if --dump-slave , start the slave sql thread */ if (opt_slave_data && do_start_slave_sql(mysql)) goto err; But I don't know what was meant to be done under if, so I'll leave it to serg to fix as initially intended.

          People

            serg Sergei Golubchik
            jb-boin Jean Weisbuch
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              Updated:
              Resolved:

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