Crash in sst_auth_real_set with SET @@global.wsrep_sst_auth= NULL

[Philip Stoev]

When running the MariaDB wsrep.variables test suite while the wsrep library was not loaded at all caused the following crash

==13312== Thread 18:
==13312== Invalid read of size 1
==13312== at 0x4A092F2: strlen (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==13312== by 0x3F2D88612D: strdup (in /usr/lib64/libc-2.18.so)
==13312== by 0x63324D: sst_auth_real_set(char const*) (wsrep_sst.cc:125)
==13312== by 0x633309: wsrep_sst_auth_update(sys_var*, THD*, enum_var_type) (wsrep_sst.cc:152)
==13312== by 0x72CCF5: sys_var::update(THD*, set_var*) (set_var.cc:194)
==13312== by 0x72DD5D: set_var::update(THD*) (set_var.cc:670)
==13312== by 0x72D936: sql_set_variables(THD*, List<set_var_base>*) (set_var.cc:573)
==13312== by 0x7D8D3B: mysql_execute_command(THD*) (sql_parse.cc:4075)
==13312== by 0x7E0BA6: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:6815)
==13312== by 0x7E01B0: wsrep_mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:6595)
==13312== by 0x7D251D: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1525)
==13312== by 0x7D1039: do_command(THD*) (sql_parse.cc:1114)
==13312== by 0x79BC6B: do_handle_one_connection(THD*) (sql_connect.cc:1007)
==13312== by 0x79B762: handle_one_connection (sql_connect.cc:916)
==13312== by 0xAC697E: pfs_spawn_thread (pfs.cc:1860)
==13312== by 0x3F2E007F34: start_thread (in /usr/lib64/libpthread-2.18.so)
==13312== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==13312==

[Philip Stoev (philip-stoev-f)]

To reproduce, just pipe the attached mysqltestcase though the mysql client (with --force) and it will crash regardless of the SQL errors that may be displayed.

[Nirbhay Choubey (nirbhay)]

https://mariadb.atlassian.net/browse/MDEV-6411