out-of-bound array access fixed

mysql-test/r/type_float.result

@@ -105,6 +105,18 @@ select min(a) from t1;
 min(a)
 -0.010
 drop table t1;
+create table t1 (a float(200,100), b double(200,100));
+insert t1 values (1.0, 2.0);
+select * from t1;
+a	b
+1.000000000000000000000000000000	2.000000000000000000000000000000
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` float(200,30) default NULL,
+  `b` double(200,30) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
 create table t1 (f float(54));
 ERROR 42000: Incorrect column specifier for column 'f'
 drop table if exists t1;

mysql-test/t/type_float.test

@@ -54,6 +54,12 @@ select a from t1 order by a;
 select min(a) from t1;
 drop table t1;
 
+create table t1 (a float(200,100), b double(200,100));
+insert t1 values (1.0, 2.0);
+select * from t1;
+show create table t1;
+drop table t1;
+
 # Errors
 
 --error 1063

sql/field.cc

@@ -2307,7 +2307,8 @@ int Field_float::store(double nr)
     }
     else
     {
-      max_value= (log_10[field_length]-1)/log_10[dec];
+      uint tmp=min(field_length,array_elements(log_10)-1);
+      max_value= (log_10[tmp]-1)/log_10[dec];
       /*
 	The following comparison is needed to not get an overflow if nr
 	is close to FLT_MAX
@@ -2607,7 +2608,8 @@ int Field_double::store(double nr)
     }
     else
     {
-      max_value= (log_10[field_length]-1)/log_10[dec];
+      uint tmp=min(field_length,array_elements(log_10)-1);
+      max_value= (log_10[tmp]-1)/log_10[dec];
       if (fabs(nr) < DBL_MAX/10.0e+32)
 	nr= floor(nr*log_10[dec]+0.5)/log_10[dec];
     }