Some details from my attempt to investigate

So, in memcpy_field_possible() we crash at this line:

const enum_field_types to_type= from->type();

Let's assume for the sake of investigation that from=NULL (or an invalid pointer)
the caller function is:

int field_conv(Field *to,Field *from)

keep the assumption, from=NULL. The caller is:

static int save_field_in_field(Field *from, bool *null_value,
Field *to, bool no_conversions)

which has:

res= field_conv(to, from);

however, above that, the function has:

if (from->is_null())
{
...

if we had from==NULL here, we would have crashed earlier.

 class Field_string :public Field_longstr {
 ...
   enum_field_types type() const
   {
     return ((can_alter_field_type && orig_table &&
              orig_table->s->db_create_options & HA_OPTION_PACK_RECORD &&
       field_length >= 4) &&
             orig_table->s->frm_version < FRM_VER_TRUE_VARCHAR ?
      MYSQL_TYPE_VAR_STRING : MYSQL_TYPE_STRING);
 ^ we crash here

it seems, the function is called for valid Field objects: at the start of memcpy_field_possible(), there are these calls:

   const enum_field_types to_real_type= to->real_type();
   const enum_field_types from_real_type= from->real_type();

and we didn't crash there. real_type() have trivial

implementations, so the fact that they succeeded only means that field object is valid.

The call to from->type() crashes. I assume that orig_table has invalid value.

It was probably invalid in 5.5 also. But, before the fix for MDEV-4309 the call to from->type() was at the end of if-condition, so execution simply didn't reach it.

MDEV-4309 moved the call to start of the function, and now it crashes.

The patch is at
https://code.launchpad.net/~maria-captains/maria/10.0-csc8034-r1

We've got a script that allows to repeat the problem: see CSC#8034, stress_minimal.sql.

I was using 10.0.13, compiled with "cmake . ; make " and I got:

./mysqld(my_print_stacktrace+0x24)[0xac2584]
./mysqld(handle_fatal_signal+0x3d8)[0x6ecf68]
/lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x7f17fa45acb0]
./mysqld(_ZNK12Field_string4typeEv+0x1a)[0x6e605a]
./mysqld(_Z21memcpy_field_possibleP5FieldS0_+0x4c)[0x6e8f2c]
./mysqld(_Z10field_convP5FieldS0_+0x19)[0x6e9449]
./mysqld[0x6fe6c9]
./mysqld(_Z12sp_eval_exprP3THDP5FieldPP4Item+0x7e)[0x7d9b1e]
./mysqld(_ZN11sp_rcontext12set_variableEP3THDP5FieldPP4Item+0x17)[0x7e0cd7]
./mysqld(_ZN9sp_cursor24Select_fetch_into_spvars9send_dataER4ListI4ItemE+0x56)[0x7e0d56]
./mysqld(_ZN19Materialized_cursor5fetchEm+0x4c)[0x7ec1dc]
./mysqld(_ZN9sp_cursor5fetchEP3THDP4ListI11sp_variableE+0x4f)[0x7e110f]
./mysqld(_ZN15sp_instr_cfetch7executeEP3THDPj+0x2f)[0x7d7a3f]
./mysqld(_ZN7sp_head7executeEP3THDb+0x754)[0x7dac04]
./mysqld(_ZN7sp_head17execute_procedureEP3THDP4ListI4ItemE+0x581)[0x7dbf61]
./mysqld(_Z21mysql_execute_commandP3THD+0x3178)[0x5b5038]
./mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x169)[0x5b9bc9]
./mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x16f9)[0x5bb3a9]
./mysqld(_Z24do_handle_one_connectionP3THD+0x1e4)[0x668ae4]
./mysqld(handle_one_connection+0x40)[0x668b70]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x7f17fa452e9a]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f17f93463fd]

Hi,
I've seen identical crash call stack that people has got win 10.0.20

mysqld.exe!Field_string::type() Line 2279 + 0x15 bytes C++
> mysqld.exe!memcpy_field_possible(Field * to, Field * from) Line 865 + 0xe9 bytes C++
mysqld.exe!field_conv(Field * to, Field * from) Line 873 + 0x5 bytes C++
mysqld.exe!save_field_in_field(Field * from, bool * null_value, Field * to, bool no_conversions) Line 5919 C++
mysqld.exe!sp_eval_expr(THD * thd, Field * result_field, Item * * expr_item_ptr) Line 434 C++
mysqld.exe!sp_rcontext::set_variable(THD * thd, Field * field, Item * * value) Line 378 + 0xe bytes C++
mysqld.exe!sp_cursor::Select_fetch_into_spvars::send_data(List<Item> & items) Line 554 + 0x25 bytes C++
mysqld.exe!Materialized_cursor::fetch(unsigned long num_rows) Line 344 + 0x10 bytes C++
mysqld.exe!sp_cursor::fetch(THD * thd, List<sp_variable> * vars) Line 511 C++
mysqld.exe!sp_instr_cfetch::execute(THD * thd, unsigned int * nextp) Line 3874 + 0xe bytes C++
mysqld.exe!sp_head::execute(THD * thd, bool merge_da_on_success) Line 1371 + 0x11 bytes C++
mysqld.exe!sp_head::execute_procedure(THD * thd, List<Item> * args) Line 2159 + 0xe bytes C++
mysqld.exe!mysql_execute_command(THD * thd) Line 4701 + 0x13 bytes C++
mysqld.exe!mysql_parse(THD * thd, char * rawbuf, unsigned int length, Parser_state * parser_state) Line 6534 C++
mysqld.exe!dispatch_command(enum_server_command command, THD * thd, char * packet, unsigned int packet_length) Line 1311 C++
mysqld.exe!do_command(THD * thd) Line 1007 C++
mysqld.exe!threadpool_process_request(THD * thd) Line 233 + 0x8 bytes C++
mysqld.exe!io_completion_callback(_TP_CALLBACK_INSTANCE * instance, void * context, void * overlapped, unsigned long io_result, unsigned __int64 nbytes, _TP_IO * io) Line 568 + 0x17 bytes C++
kernel32.dll!00000000773b32e2()
[Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll]
00000007f9a3fa80()
0000000806034c30()
ntdll.dll!00000000774afbf0()
00000007768b8c80()

Might be that bug needs to be re-open

Reopening due to reports that the crash is still observable.

Lawrin Novitsky , can you post the stack trace here? I have succeded in loading the minidump into WinDbg but couldn't get any further..

The reason for asking is that I've now got a patch for MDEV-7040.

Ok it was a misunderstanding, the stack trace is as posted above in the comment dated 2015-07-06 17:23. This is supposed to be fixed by MDEV-7040.