REPAIR TABLE on MyISAM fails with SIGSEGV's in Item_func_concat::append_value, Item_func_concat::val_str, and ha_maria::drop_table and UBSAN: member access within null pointer in Item_func_concat::append_value

SET sql_mode='', myisam_repair_threads=2;

CREATE TABLE t (id INT,a VARCHAR(1),b VARCHAR(1),c VARCHAR(1) GENERATED ALWAYS AS (CONCAT (a,b)),KEY(c)) ENGINE=MyISAM;

INSERT INTO t VALUES (0,0,9687,0);

REPAIR TABLE t QUICK;

Core was generated by `/test/MD160821-mariadb-10.7.0-linux-x86_64-dbg/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  0x000055f10f57baff in Item_func_concat::append_value (

    this=this@entry=0x1483cc026178, thd=thd@entry=0x0, 

    res=res@entry=0x1483cc0261a0, app=0x1483cc026088)

    at /test/10.7_dbg/sql/sql_string.h:274

[Current thread is 1 (Thread 0x1483eedfe700 (LWP 2336320))]

(gdb) bt

#0  0x000055f10f57baff in Item_func_concat::append_value (this=this@entry=0x1483cc026178, thd=thd@entry=0x0, res=res@entry=0x1483cc0261a0, app=0x1483cc026088) at /test/10.7_dbg/sql/sql_string.h:274

#1  0x000055f10f57bea8 in Item_func_concat::val_str (this=0x1483cc026178, str=0x1483cc0261a0) at /test/10.7_dbg/sql/item_strfunc.cc:628

#2  0x000055f10f4ca49b in Item::save_str_in_field (this=0x1483cc026178, field=0x1483cc025440, no_conversions=<optimized out>) at /test/10.7_dbg/sql/item.cc:6664

#3  0x000055f10f3a3b08 in Type_handler_string_result::Item_save_in_field (this=<optimized out>, item=<optimized out>, field=<optimized out>, no_conversions=<optimized out>) at /test/10.7_dbg/sql/sql_type.cc:4330

#4  0x000055f10f4b0847 in Item::save_in_field (this=0x1483cc026178, field=0x1483cc025440, no_conversions=<optimized out>) at /test/10.7_dbg/sql/item.cc:6712

#5  0x000055f10f2cb9eb in TABLE::update_virtual_field (this=this@entry=0x1483cc0242d8, vf=0x1483cc025440) at /test/10.7_dbg/sql/table.cc:8770

#6  0x000055f10fc1f36b in compute_vcols (info=0x1483cc0271f8, record=<optimized out>, keynum=<optimized out>) at /test/10.7_dbg/storage/myisam/ha_myisam.cc:710

#7  0x000055f10fc25b49 in sort_get_next_record (sort_param=sort_param@entry=0x1483cc0b6038) at /test/10.7_dbg/storage/myisam/mi_check.c:3672

#8  0x000055f10fc2afec in sort_key_read (sort_param=0x1483cc0b6038, key=0x1483c0000dd0) at /test/10.7_dbg/storage/myisam/mi_check.c:3135

#9  0x000055f10fc60342 in thr_find_all_keys_exec (sort_param=0x1483cc0b6038) at /test/10.7_dbg/storage/myisam/sort.c:451

#10 thr_find_all_keys (arg=0x1483cc0b6038) at /test/10.7_dbg/storage/myisam/sort.c:510

#11 0x00001484134e4609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#12 0x00001484130d2293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Core was generated by `/test/MD160821-mariadb-10.7.0-linux-x86_64-opt/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  0x00005620e730915b in Item_func_concat::append_value (this=0x15126c01cf08, 

    thd=0x0, res=0x15126c01cf30, app=0x15126c01ce18)

    at /test/10.7_opt/sql/sql_string.h:274

[Current thread is 1 (Thread 0x1512999fc700 (LWP 2388670))]

(gdb) bt

#0  0x00005620e730915b in Item_func_concat::append_value (this=0x15126c01cf08, thd=0x0, res=0x15126c01cf30, app=0x15126c01ce18) at /test/10.7_opt/sql/sql_string.h:274

#1  0x00005620e73092fe in Item_func_concat::val_str (this=0x15126c01cf08, str=0x15126c01cf30) at /test/10.7_opt/sql/item_strfunc.cc:626

#2  0x00005620e7282425 in Item::save_str_in_field (this=0x15126c01cf08, field=0x15126c017e20, no_conversions=<optimized out>) at /test/10.7_opt/sql/item.cc:6664

#3  0x00005620e72721d7 in Item::save_in_field (this=0x15126c01cf08, field=0x15126c017e20, no_conversions=<optimized out>) at /test/10.7_opt/sql/item.cc:6712

#4  0x00005620e710dc31 in TABLE::update_virtual_field (this=this@entry=0x15126c01b6d8, vf=0x15126c017e20) at /test/10.7_opt/sql/table.cc:8770

#5  0x00005620e772bcb7 in compute_vcols (info=0x15126c01dda8, record=<optimized out>, keynum=<optimized out>) at /test/10.7_opt/storage/myisam/ha_myisam.cc:710

#6  0x00005620e77328a4 in sort_get_next_record (sort_param=sort_param@entry=0x15126c083928) at /test/10.7_opt/storage/myisam/mi_check.c:3672

#7  0x00005620e7738ac5 in sort_key_read (sort_param=0x15126c083928, key=0x151270000c70) at /test/10.7_opt/storage/myisam/mi_check.c:3135

#8  0x00005620e7769b0f in thr_find_all_keys_exec (sort_param=0x15126c083928) at /test/10.7_opt/storage/myisam/sort.c:451

#9  thr_find_all_keys (arg=0x15126c083928) at /test/10.7_opt/storage/myisam/sort.c:510

#10 0x00001512be3e1609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#11 0x00001512bdfcf293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Core was generated by `/test/MD160821-mariadb-10.6.5-linux-x86_64-dbg/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  0x000056280e8c9637 in Item_func_concat::append_value (

    this=this@entry=0x15106c0270c8, thd=thd@entry=0x0, 

    res=res@entry=0x15106c0270f0, app=0x15106c026fd8)

    at /test/10.6_dbg/sql/sql_string.h:274

[Current thread is 1 (Thread 0x15108e7fb700 (LWP 2388769))]

(gdb) bt

#0  0x000056280e8c9637 in Item_func_concat::append_value (this=this@entry=0x15106c0270c8, thd=thd@entry=0x0, res=res@entry=0x15106c0270f0, app=0x15106c026fd8) at /test/10.6_dbg/sql/sql_string.h:274

#1  0x000056280e8c99e0 in Item_func_concat::val_str (this=0x15106c0270c8, str=0x15106c0270f0) at /test/10.6_dbg/sql/item_strfunc.cc:628

#2  0x000056280e81760b in Item::save_str_in_field (this=0x15106c0270c8, field=0x15106c0263b0, no_conversions=<optimized out>) at /test/10.6_dbg/sql/item.cc:6664

#3  0x000056280e6f1412 in Type_handler_string_result::Item_save_in_field (this=<optimized out>, item=<optimized out>, field=<optimized out>, no_conversions=<optimized out>) at /test/10.6_dbg/sql/sql_type.cc:4330

#4  0x000056280e7fd9b5 in Item::save_in_field (this=0x15106c0270c8, field=0x15106c0263b0, no_conversions=<optimized out>) at /test/10.6_dbg/sql/item.cc:6712

#5  0x000056280e619e71 in TABLE::update_virtual_field (this=this@entry=0x15106c025268, vf=0x15106c0263b0) at /test/10.6_dbg/sql/table.cc:8770

#6  0x000056280efb7d5b in compute_vcols (info=0x15106c028108, record=<optimized out>, keynum=<optimized out>) at /test/10.6_dbg/storage/myisam/ha_myisam.cc:710

#7  0x000056280efbe539 in sort_get_next_record (sort_param=sort_param@entry=0x15106c0b6b88) at /test/10.6_dbg/storage/myisam/mi_check.c:3672

#8  0x000056280efc39dc in sort_key_read (sort_param=0x15106c0b6b88, key=0x151060000dd0) at /test/10.6_dbg/storage/myisam/mi_check.c:3135

#9  0x000056280eff8d32 in thr_find_all_keys_exec (sort_param=0x15106c0b6b88) at /test/10.6_dbg/storage/myisam/sort.c:451

#10 thr_find_all_keys (arg=0x15106c0b6b88) at /test/10.6_dbg/storage/myisam/sort.c:510

#11 0x00001510b2f6a609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#12 0x00001510b2b58293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Core was generated by `/test/MD160821-mariadb-10.2.41-linux-x86_64-opt/bin/mysqld --no-defaults --core'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=11)

    at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

[Current thread is 1 (Thread 0x150eb74b0700 (LWP 2388689))]

(gdb) bt

#0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=11) at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

#1  0x0000563051a3d69f in my_write_core (sig=sig@entry=11) at /test/10.2_opt/mysys/stacktrace.c:382

#2  0x00005630514e2628 in handle_fatal_signal (sig=11) at /test/10.2_opt/sql/signal_handler.cc:355

#3  <signal handler called>

#4  0x000056305157a97f in Item_func_concat::val_str (this=0x150e9001a780, str=0x150e9001a7b0) at /test/10.2_opt/sql/sql_string.h:198

#5  0x00005630514f31ca in Item::save_in_field (this=0x150e9001a780, field=0x150e90017998, no_conversions=<optimized out>) at /test/10.2_opt/sql/item.cc:6397

#6  0x00005630513efc34 in TABLE::update_virtual_field (this=this@entry=0x150e900194c8, vf=0x150e90017998) at /test/10.2_opt/sql/table.cc:7830

#7  0x0000563051940c63 in compute_vcols (info=<optimized out>, record=<optimized out>, keynum=<optimized out>) at /test/10.2_opt/storage/myisam/ha_myisam.cc:683

#8  0x0000563051948874 in sort_get_next_record (sort_param=sort_param@entry=0x150e900592a8) at /test/10.2_opt/storage/myisam/mi_check.c:3667

#9  0x000056305194e8e5 in sort_key_read (sort_param=0x150e900592a8, key=0x150e88000c60) at /test/10.2_opt/storage/myisam/mi_check.c:3131

#10 0x0000563051980172 in thr_find_all_keys_exec (sort_param=0x150e900592a8) at /test/10.2_opt/storage/myisam/sort.c:450

#11 thr_find_all_keys (arg=0x150e900592a8) at /test/10.2_opt/storage/myisam/sort.c:509

#12 0x0000150eee82e609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#13 0x0000150eee424293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95