here is full stack

(gdb) bt
#0  0x0000003e6307bf0b in memcpy () from /lib64/libc.so.6
#1  0x000000000093ae0c in _mi_rec_pack (info=0x7fff90011f60, to=0x7fff03fff028 "", from=0x7fff90015c4f "")
    at /tmp/Percona-Server-5.5.18-rel23.0/storage/myisam/mi_dynrec.c:997
#2  0x000000000093dc1d in _mi_write_blob_record (info=0x7fff90011f60, record=0x7fff900159a0 "\370\v\252\002")
    at /tmp/Percona-Server-5.5.18-rel23.0/storage/myisam/mi_dynrec.c:289
#3  0x0000000000956b7f in mi_write (info=0x7fff90011f60, record=0x7fff900159a0 "\370\v\252\002")
    at /tmp/Percona-Server-5.5.18-rel23.0/storage/myisam/mi_write.c:142
#4  0x0000000000925523 in ha_myisam::write_row (this=0x7fff90011940, buf=0x7fff900159a0 "\370\v\252\002")
    at /tmp/Percona-Server-5.5.18-rel23.0/storage/myisam/ha_myisam.cc:789
#5  0x0000000000689a0f in handler::ha_write_row (this=0x7fff90011940, buf=0x7fff900159a0 "\370\v\252\002")
    at /tmp/Percona-Server-5.5.18-rel23.0/sql/handler.cc:4980
#6  0x00000000005bfedd in schema_table_store_record (table=<optimized out>, thd=<optimized out>)
    at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_show.cc:2756
#7  fill_schema_processlist (thd=0x7fff9402d870, tables=<optimized out>, cond=<optimized out>)
    at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_show.cc:2056
#8  0x00000000005ac671 in get_schema_tables_result (join=0x7fff900196e8, executed_place=PROCESSED_BY_JOIN_EXEC)
    at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_show.cc:7420
#9  0x00000000005a78e6 in JOIN::exec (this=0x7fff900196e8) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_select.cc:1926
#10 0x00000000005a9c22 in mysql_select (thd=0x7fff9402d870, rref_pointer_array=0x7fff9402fce8, tables=0x7fff8c03e808, wild_num=0, 
    fields=<optimized out>, conds=0x7fff8c03f470, og_num=1, order=0x7fff8c03f668, group=0x0, having=0x0, proc_param=0x0, select_options=2684619520, 
    result=0x7fff8c03f730, unit=0x7fff9402f4f8, select_lex=0x7fff9402fb18) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_select.cc:2600
#11 0x00000000005aa64b in handle_select (thd=0x7fff9402d870, lex=0x7fff9402f438, result=0x7fff8c03f730, setup_tables_done_option=0)
    at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_select.cc:312
#12 0x00000000005661d0 in execute_sqlcom_select (thd=0x7fff9402d870, all_tables=0x7fff8c03e808)
    at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_parse.cc:4735
#13 0x0000000000568f90 in mysql_execute_command (thd=0x7fff9402d870) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_parse.cc:2279
#14 0x000000000056e49d in mysql_parse (thd=0x7fff9402d870, 
    rawbuf=0x7fff8c03e4c0 "select id from information_schema.processlist where id<>connection_id()  and info like 'select%' order by rand() limit 1 into @a", length=<optimized out>, parser_state=0x4a920db0) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_parse.cc:5805
#15 0x000000000056f87a in dispatch_command (command=COM_QUERY, thd=0x7fff9402d870, 
    packet=0x7fff94064e51 "select id from information_schema.processlist where id<>connection_id()  and info like 'select%' order by rand() limit 1 into @a;", packet_length=<optimized out>) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_parse.cc:1060
#16 0x000000000056fbd6 in do_command (thd=0x7fff9402d870) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_parse.cc:788
#17 0x000000000060c775 in do_handle_one_connection (thd_arg=0x7fff9402d870) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_connect.cc:1409
---Type <return> to continue, or q <return> to quit---
#18 0x000000000060c89c in handle_one_connection (arg=<optimized out>) at /tmp/Percona-Server-5.5.18-rel23.0/sql/sql_connect.cc:1315
#19 0x0000003e638064a7 in start_thread () from /lib64/libpthread.so.0
#20 0x0000003e630d3c2d in clone () from /lib64/libc.so.6
#21 0x0000000000000000 in ?? ()
(gdb) up
#1  0x000000000093ae0c in _mi_rec_pack (info=0x7fff90011f60, to=0x7fff03fff028 "", from=0x7fff90015c4f "")
    at /tmp/Percona-Server-5.5.18-rel23.0/storage/myisam/mi_dynrec.c:997
997               memcpy(to+tmp_length,temp_pos,(size_t) blob->length);
(gdb) p *blob
$17 = {offset = 687, pack_length = 4, length = 2147483648}