diff --git a/mysql-test/r/func_time.result b/mysql-test/r/func_time.result
index a82cf3c19c2..563212cb756 100644
--- a/mysql-test/r/func_time.result
+++ b/mysql-test/r/func_time.result
@@ -989,6 +989,12 @@ ADDTIME('916:40:00', '416:40:00')
 Warnings:
 Warning	1292	Truncated incorrect time value: '916:40:00'
 Warning	1292	Truncated incorrect time value: '1255:39:59.999999'
+SELECT ADDTIME(20010101,1e0), ADDTIME(20010101,1.1e0);
+ADDTIME(20010101,1e0)	ADDTIME(20010101,1.1e0)
+2001-01-01 00:00:01	2001-01-01 00:00:01.100000
+SELECT ADDTIME(ADDTIME(20010101,1e0), 0);
+ADDTIME(ADDTIME(20010101,1e0), 0)
+2001-01-01 00:00:01
 SELECT SUBTIME('916:40:00', '416:40:00');
 SUBTIME('916:40:00', '416:40:00')
 422:19:59.999999
diff --git a/mysql-test/r/type_newdecimal.result b/mysql-test/r/type_newdecimal.result
index 0fbf64a4b18..0df2b59d832 100644
--- a/mysql-test/r/type_newdecimal.result
+++ b/mysql-test/r/type_newdecimal.result
@@ -2456,5 +2456,29 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 #
+# MDEV-25317 Assertion `scale <= precision' failed in
+# decimal_bin_size And Assertion `scale >= 0 && precision > 0 && scale <= precision'
+# failed in decimal_bin_size_inline/decimal_bin_size.
+#
+SELECT AVG(DISTINCT 0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001);
+AVG(DISTINCT 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+0.00000000000000000000000000000000000000
+CREATE TABLE t1 AS SELECT NULL AS v1;
+SELECT 1 FROM t1 GROUP BY v1 ORDER BY AVG ( from_unixtime ( '' ) ) ;
+1
+1
+Warnings:
+Warning	1292	Truncated incorrect DECIMAL value: ''
+DROP TABLE t1;
+SELECT SUM(DISTINCT 0.000000000000000000000000000000000000001);
+SUM(DISTINCT 0.000000000000000000000000000000000000001)
+0.00000000000000000000000000000000000000
+CREATE TABLE t1 AS SELECT 1.000000000000000000000000000000000 AS a;
+ALTER TABLE t1 ADD COLUMN b INT;
+SELECT ROUND (a,b) AS c FROM t1 ORDER BY c;
+c
+NULL
+DROP TABLE t1;
+#
 # End of 10.2 tests
 #
diff --git a/mysql-test/t/func_time.test b/mysql-test/t/func_time.test
index 22729b4300b..7f35e658d1b 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -513,6 +513,10 @@ SELECT TIME_TO_SEC('916:40:00');
 SELECT ADDTIME('500:00:00', '416:40:00');
 SELECT ADDTIME('916:40:00', '416:40:00');
 
+# check if ADDTIME() handles NOT_FIXED_DEC correctly
+SELECT ADDTIME(20010101,1e0), ADDTIME(20010101,1.1e0);
+SELECT ADDTIME(ADDTIME(20010101,1e0), 0);
+
 # check if SUBTIME() handles out-of-range values correctly
 SELECT SUBTIME('916:40:00', '416:40:00');
 SELECT SUBTIME('-916:40:00', '416:40:00');
diff --git a/mysql-test/t/type_newdecimal.test b/mysql-test/t/type_newdecimal.test
index e5d903e95cd..a5cb15e1a2c 100644
--- a/mysql-test/t/type_newdecimal.test
+++ b/mysql-test/t/type_newdecimal.test
@@ -1894,6 +1894,25 @@ show create table t1;
 
 drop table t1;
 
+--echo #
+--echo # MDEV-25317 Assertion `scale <= precision' failed in
+--echo # decimal_bin_size And Assertion `scale >= 0 && precision > 0 && scale <= precision'
+--echo # failed in decimal_bin_size_inline/decimal_bin_size.
+--echo #
+
+SELECT AVG(DISTINCT 0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001);
+
+CREATE TABLE t1 AS SELECT NULL AS v1;
+SELECT 1 FROM t1 GROUP BY v1 ORDER BY AVG ( from_unixtime ( '' ) ) ;
+DROP TABLE t1;
+
+SELECT SUM(DISTINCT 0.000000000000000000000000000000000000001);
+
+CREATE TABLE t1 AS SELECT 1.000000000000000000000000000000000 AS a;
+ALTER TABLE t1 ADD COLUMN b INT;
+SELECT ROUND (a,b) AS c FROM t1 ORDER BY c;
+DROP TABLE t1;
+
 --echo #
 --echo # End of 10.2 tests
 --echo #
diff --git a/sql/field.cc b/sql/field.cc
index 74317a4d70b..07212a53b45 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -3103,6 +3103,15 @@ Field *Field_decimal::make_new_field(MEM_ROOT *root, TABLE *new_table,
 }
 
 
+void Field_new_decimal::set_and_validate_prec(uint32 len_arg,
+  uint8 dec_arg, bool unsigned_arg)
+{
+  precision= my_decimal_length_to_precision(len_arg, dec_arg, unsigned_arg);
+  set_if_smaller(precision, DECIMAL_MAX_PRECISION);
+  bin_size= my_decimal_get_binary_size(precision, dec);
+}
+
+
 /****************************************************************************
 ** Field_new_decimal
 ****************************************************************************/
@@ -3115,13 +3124,10 @@ Field_new_decimal::Field_new_decimal(uchar *ptr_arg,
                                      uint8 dec_arg,bool zero_arg,
                                      bool unsigned_arg)
   :Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
-             unireg_check_arg, field_name_arg, dec_arg, zero_arg, unsigned_arg)
+             unireg_check_arg, field_name_arg,
+             MY_MIN(dec_arg, DECIMAL_MAX_SCALE), zero_arg, unsigned_arg)
 {
-  precision= my_decimal_length_to_precision(len_arg, dec_arg, unsigned_arg);
-  set_if_smaller(precision, DECIMAL_MAX_PRECISION);
-  DBUG_ASSERT((precision <= DECIMAL_MAX_PRECISION) &&
-              (dec <= DECIMAL_MAX_SCALE));
-  bin_size= my_decimal_get_binary_size(precision, dec);
+  set_and_validate_prec(len_arg, dec_arg, unsigned_arg);
 }
 
 
@@ -3132,13 +3138,11 @@ Field_new_decimal::Field_new_decimal(uint32 len_arg,
                                      bool unsigned_arg)
   :Field_num((uchar*) 0, len_arg,
              maybe_null_arg ? (uchar*) "": 0, 0,
-             NONE, name, dec_arg, 0, unsigned_arg)
+             NONE, name,
+             MY_MIN(dec_arg, DECIMAL_MAX_SCALE), 0, unsigned_arg)
 {
-  precision= my_decimal_length_to_precision(len_arg, dec_arg, unsigned_arg);
-  set_if_smaller(precision, DECIMAL_MAX_PRECISION);
-  DBUG_ASSERT((precision <= DECIMAL_MAX_PRECISION) &&
-              (dec <= DECIMAL_MAX_SCALE));
-  bin_size= my_decimal_get_binary_size(precision, dec);
+  DBUG_ASSERT(dec <= DECIMAL_MAX_SCALE);
+  set_and_validate_prec(len_arg, dec_arg, unsigned_arg);
 }
 
 
diff --git a/sql/field.h b/sql/field.h
index 78b6dcb516b..ad01b2ff642 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -1913,6 +1913,8 @@ public:
 class Field_new_decimal :public Field_num {
 private:
   int do_save_field_metadata(uchar *first_byte);
+  void set_and_validate_prec(uint32 len_arg,
+                             uint8 dec_arg, bool unsigned_arg);
 public:
   /* The maximum number of decimal digits can be stored */
   uint precision;
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 7a7eaf9dc23..4e28e8e9528 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -2453,14 +2453,16 @@ bool Item_func_round::fix_length_and_dec()
   if (!args[1]->const_item())
   {
     decimals= args[0]->decimals;
-    max_length= float_length(decimals);
     if (args[0]->result_type() == DECIMAL_RESULT)
     {
-      max_length++;
+      max_length= args[0]->max_length;
       set_handler_by_result_type(DECIMAL_RESULT);
     }
     else
+    {
+      max_length= float_length(decimals);
       set_handler_by_result_type(REAL_RESULT);
+    }
     return FALSE;
   }
 
diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index dd65f04a652..77224d5321d 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -1346,6 +1346,8 @@ bool Item_sum_sum::fix_length_and_dec()
   {
     /* SUM result can't be longer than length(arg) + length(MAX_ROWS) */
     int precision= args[0]->decimal_precision() + DECIMAL_LONGLONG_DIGITS;
+    decimals= MY_MIN(decimals, DECIMAL_MAX_SCALE);
+    precision= MY_MIN(precision, DECIMAL_MAX_PRECISION);
     max_length= my_decimal_precision_to_length_no_truncation(precision,
                                                              decimals,
                                                              unsigned_flag);
@@ -1673,12 +1675,12 @@ bool Item_sum_avg::fix_length_and_dec()
   if (Item_sum_avg::result_type() == DECIMAL_RESULT)
   {
     int precision= args[0]->decimal_precision() + prec_increment;
-    decimals= MY_MIN(args[0]->decimals + prec_increment, DECIMAL_MAX_SCALE);
+    decimals= MY_MIN(args[0]->decimal_scale() + prec_increment, DECIMAL_MAX_SCALE);
     max_length= my_decimal_precision_to_length_no_truncation(precision,
                                                              decimals,
                                                              unsigned_flag);
     f_precision= MY_MIN(precision+DECIMAL_LONGLONG_DIGITS, DECIMAL_MAX_PRECISION);
-    f_scale=  args[0]->decimals;
+    f_scale= args[0]->decimal_scale();
     dec_bin_size= my_decimal_get_binary_size(f_precision, f_scale);
   }
   else
diff --git a/sql/sql_type.cc b/sql/sql_type.cc
index c1f192b0622..b1e141d0eeb 100644
--- a/sql/sql_type.cc
+++ b/sql/sql_type.cc
@@ -258,7 +258,6 @@ Type_handler_decimal_result::make_num_distinct_aggregator_field(
                                                             const Item *item)
                                                             const
 {
-  DBUG_ASSERT(item->decimals <= DECIMAL_MAX_SCALE);
   return new (mem_root)
          Field_new_decimal(NULL, item->max_length,
                            (uchar *) (item->maybe_null ? "" : 0),