Bug #38570 calling UDF causes a server crash

Description:
I worked on bug #38257

SELECT udf_real_max_length();
080805 13:22:20 - mysqld got signal 10 ;
....
ERROR 2013 (HY000): Lost connection to MySQL server during query

How to repeat:
FIle: udf_return_values.c
-------------------------
#include <string.h>

#include <my_global.h>
#include <mysql.h>

#if defined(_WIN32) || defined(_WIN64)
#define DLLEXP __declspec(dllexport)
#else
#define DLLEXP /* no dll */
#endif

#ifdef __cplusplus
extern "C" {
#endif
DLLEXP my_bool udf_int_max_length_init(UDF_INIT *initid){
  return 0;
}

DLLEXP longlong udf_int_max_length(
  UDF_INIT *initid, UDF_ARGS *args,
  my_bool *is_null, my_bool *error
){
  return initid->max_length;
}

DLLEXP my_bool udf_real_max_length_init(UDF_INIT *initid){
  initid->decimals = 0;
  return 0;
}

DLLEXP double udf_real_max_length(
  UDF_INIT *initid, UDF_ARGS *args,
  my_bool *is_null, my_bool *error
){
  initid->decimals = 0;
  return (double)initid->max_length;
}

DLLEXP my_bool udf_str_max_length_init(UDF_INIT *initid){
  initid->decimals = 0;
  return 0;
}

DLLEXP char* udf_str_max_length(
  UDF_INIT *initid, UDF_ARGS *args,
  char* buffer, unsigned long* length,
  my_bool *is_null, my_bool *error
){
  initid->decimals = 0; 
  sprintf(buffer, "%u\0", initid->max_length);
  *length = strlen(buffer);
  return buffer;
}
#ifdef __cplusplus
}
#endif

Compile:
--------
gcc -Wall -I/opt/mysql/mysql/include -shared -o udf_return_values.so udf_return_values.c

Move udf_return_values.so to plugin dir
---------------------------------------

CREATE FUNCTION udf_real_max_length RETURNS REAL soname 'udf_return_values.so';
Query OK, 0 rows affected (0.00 sec)

SELECT udf_real_max_length();

Omer,

Regression was noticed with 5.0.22 see bug and my comment below:

http://bugs.mysql.com/bug.php?id=38257

[21 Jul 20:03] Miguel Solorzano

Thanks.