Fix for BUG#27592: stack overrun when storing datetime value

using prepared statements.


sql/field.cc:
  Using MAX_DATETIME_WIDTH or MAX_DATETIME_COMPRESSED_WIDTH
  constants for the length of DATETIME fields.
  
  Using MAX_DATE_STRING_REP_LENGTH for allocating buffers
  for date/time/... string representation.
sql/item_timefunc.cc:
  Using MAX_DATETIME_WIDTH or MAX_DATETIME_COMPRESSED_WIDTH
  constants for the length of DATETIME fields.
  
  Using MAX_DATE_STRING_REP_LENGTH for allocating buffers
  for date/time/... string representation.
sql/unireg.h:
  Introduce a constant for length of datetime compressed
  format (YYYYMMDDHHMMSS).

sql/field.cc

@@ -4285,7 +4285,7 @@ Field_timestamp::Field_timestamp(char *ptr_arg, uint32 len_arg,
 				 const char *field_name_arg,
 				 struct st_table *table_arg,
 				 CHARSET_INFO *cs)
-  :Field_str(ptr_arg, 19, null_ptr_arg, null_bit_arg,
+  :Field_str(ptr_arg, MAX_DATETIME_WIDTH, null_ptr_arg, null_bit_arg,
 	     unireg_check_arg, field_name_arg, table_arg, cs)
 {
   /* For 4.0 MYD and 4.0 InnoDB compatibility */
@@ -4303,7 +4303,8 @@ Field_timestamp::Field_timestamp(char *ptr_arg, uint32 len_arg,
 Field_timestamp::Field_timestamp(bool maybe_null_arg,
                                  const char *field_name_arg,
                                  struct st_table *table_arg, CHARSET_INFO *cs)
-  :Field_str((char*) 0, 19, maybe_null_arg ? (uchar*) "": 0, 0,
+  :Field_str((char*) 0, MAX_DATETIME_WIDTH,
+             maybe_null_arg ? (uchar*) "": 0, 0,
 	     NONE, field_name_arg, table_arg, cs)
 {
   /* For 4.0 MYD and 4.0 InnoDB compatibility */
@@ -4834,7 +4835,7 @@ String *Field_time::val_str(String *val_buffer,
 			    String *val_ptr __attribute__((unused)))
 {
   MYSQL_TIME ltime;
-  val_buffer->alloc(19);
+  val_buffer->alloc(MAX_DATE_STRING_REP_LENGTH);
   long tmp=(long) sint3korr(ptr);
   ltime.neg= 0;
   if (tmp < 0)
@@ -5370,7 +5371,7 @@ int Field_newdate::store_time(MYSQL_TIME *ltime, timestamp_type time_type)
                      (MODE_NO_ZERO_IN_DATE | MODE_NO_ZERO_DATE |
                       MODE_INVALID_DATES))), &error))
     {
-      char buff[12];
+      char buff[MAX_DATE_STRING_REP_LENGTH];
       String str(buff, sizeof(buff), &my_charset_latin1);
       make_date((DATE_TIME_FORMAT *) 0, ltime, &str);
       set_datetime_warning(MYSQL_ERROR::WARN_LEVEL_WARN, WARN_DATA_TRUNCATED,
@@ -5595,7 +5596,7 @@ int Field_datetime::store_time(MYSQL_TIME *ltime,timestamp_type time_type)
                      (MODE_NO_ZERO_IN_DATE | MODE_NO_ZERO_DATE |
                       MODE_INVALID_DATES))), &error))
     {
-      char buff[19];
+      char buff[MAX_DATE_STRING_REP_LENGTH];
       String str(buff, sizeof(buff), &my_charset_latin1);
       make_datetime((DATE_TIME_FORMAT *) 0, ltime, &str);
       set_datetime_warning(MYSQL_ERROR::WARN_LEVEL_WARN, WARN_DATA_TRUNCATED,
@@ -5669,7 +5670,7 @@ String *Field_datetime::val_str(String *val_buffer,
   part1=(long) (tmp/LL(1000000));
   part2=(long) (tmp - (ulonglong) part1*LL(1000000));
 
-  pos=(char*) val_buffer->ptr()+19;
+  pos= (char*) val_buffer->ptr() + MAX_DATETIME_WIDTH;
   *pos--=0;
   *pos--= (char) ('0'+(char) (part2%10)); part2/=10;
   *pos--= (char) ('0'+(char) (part2%10)); part3= (int) (part2 / 10);
@@ -8565,15 +8566,18 @@ bool create_field::init(THD *thd, char *fld_name, enum_field_types fld_type,
     break;
   case FIELD_TYPE_TIMESTAMP:
     if (!fld_length)
-      length= 14;  /* Full date YYYYMMDDHHMMSS */
-    else if (length != 19)
+    {
+      /* Compressed date YYYYMMDDHHMMSS */
+      length= MAX_DATETIME_COMPRESSED_WIDTH;
+    }
+    else if (length != MAX_DATETIME_WIDTH)
     {
       /*
         We support only even TIMESTAMP lengths less or equal than 14
         and 19 as length of 4.1 compatible representation.
       */
       length= ((length+1)/2)*2; /* purecov: inspected */
-      length= min(length,14); /* purecov: inspected */
+      length= min(length, MAX_DATETIME_COMPRESSED_WIDTH); /* purecov: inspected */
     }
     flags|= ZEROFILL_FLAG | UNSIGNED_FLAG;
     if (fld_default_value)
@@ -8626,7 +8630,7 @@ bool create_field::init(THD *thd, char *fld_name, enum_field_types fld_type,
     length= 10;
     break;
   case FIELD_TYPE_DATETIME:
-    length= 19;
+    length= MAX_DATETIME_WIDTH;
     break;
   case FIELD_TYPE_SET:
     {

sql/item_timefunc.cc

@@ -51,7 +51,7 @@ static bool make_datetime(date_time_format_types format, MYSQL_TIME *ltime,
 {
   char *buff;
   CHARSET_INFO *cs= &my_charset_bin;
-  uint length= 30;
+  uint length= MAX_DATE_STRING_REP_LENGTH;
 
   if (str->alloc(length))
     return 1;
@@ -1400,7 +1400,7 @@ String *Item_date::val_str(String *str)
   MYSQL_TIME ltime;
   if (get_date(&ltime, TIME_FUZZY_DATE))
     return (String *) 0;
-  if (str->alloc(11))
+  if (str->alloc(MAX_DATE_STRING_REP_LENGTH))
   {
     null_value= 1;
     return (String *) 0;
@@ -1449,7 +1449,7 @@ void Item_func_curdate::fix_length_and_dec()
 String *Item_func_curdate::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
-  if (str->alloc(11))
+  if (str->alloc(MAX_DATE_STRING_REP_LENGTH))
   {
     null_value= 1;
     return (String *) 0;
@@ -1678,7 +1678,8 @@ String *Item_func_sec_to_time::val_str(String *str)
   MYSQL_TIME ltime;
   longlong arg_val= args[0]->val_int(); 
 
-  if ((null_value=args[0]->null_value) || str->alloc(19))
+  if ((null_value=args[0]->null_value) ||
+      str->alloc(MAX_DATE_STRING_REP_LENGTH))
   {
     null_value= 1;
     return (String*) 0;
@@ -1863,6 +1864,10 @@ String *Item_func_date_format::val_str(String *str)
     size=max_length;
   else
     size=format_length(format);
+
+  if (size < MAX_DATE_STRING_REP_LENGTH)
+    size= MAX_DATE_STRING_REP_LENGTH;
+
   if (format == str)
     str= &value;				// Save result here
   if (str->alloc(size))
@@ -1906,13 +1911,14 @@ String *Item_func_from_unixtime::val_str(String *str)
   if (get_date(&time_tmp, 0))
     return 0;
 
-  if (str->alloc(20*MY_CHARSET_BIN_MB_MAXLEN))
+  if (str->alloc(MAX_DATE_STRING_REP_LENGTH))
   {
     null_value= 1;
     return 0;
   }
 
   make_datetime((DATE_TIME_FORMAT *) 0, &time_tmp, str);
+
   return str;
 }
 
@@ -1974,14 +1980,15 @@ String *Item_func_convert_tz::val_str(String *str)
 
   if (get_date(&time_tmp, 0))
     return 0;
-  
-  if (str->alloc(20*MY_CHARSET_BIN_MB_MAXLEN))
+
+  if (str->alloc(MAX_DATE_STRING_REP_LENGTH))
   {
     null_value= 1;
     return 0;
   }
-  
+
   make_datetime((DATE_TIME_FORMAT *) 0, &time_tmp, str);
+
   return str;
 }
 
@@ -2582,6 +2589,7 @@ String *Item_datetime_typecast::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
   MYSQL_TIME ltime;
+
   if (!get_arg0_date(&ltime, TIME_FUZZY_DATE) &&
       !make_datetime(ltime.second_part ? DATE_TIME_MICROSECOND : DATE_TIME, 
 		     &ltime, str))
@@ -2660,7 +2668,8 @@ String *Item_date_typecast::val_str(String *str)
   DBUG_ASSERT(fixed == 1);
   MYSQL_TIME ltime;
 
-  if (!get_arg0_date(&ltime, TIME_FUZZY_DATE) && !str->alloc(11))
+  if (!get_arg0_date(&ltime, TIME_FUZZY_DATE) &&
+      !str->alloc(MAX_DATE_STRING_REP_LENGTH))
   {
     make_date((DATE_TIME_FORMAT *) 0, &ltime, str);
     return str;
@@ -2713,7 +2722,7 @@ String *Item_func_makedate::val_str(String *str)
   {
     null_value=0;
     get_date_from_daynr(days,&l_time.year,&l_time.month,&l_time.day);
-    if (str->alloc(11))
+    if (str->alloc(MAX_DATE_STRING_REP_LENGTH))
       goto err;
     make_date((DATE_TIME_FORMAT *) 0, &l_time, str);
     return str;
@@ -2849,6 +2858,7 @@ String *Item_func_add_time::val_str(String *str)
   days= (long)(seconds/86400L);
 
   calc_time_from_sec(&l_time3, (long)(seconds%86400L), microseconds);
+
   if (!is_time)
   {
     get_date_from_daynr(days,&l_time3.year,&l_time3.month,&l_time3.day);
@@ -2964,7 +2974,7 @@ String *Item_func_maketime::val_str(String *str)
                    args[2]->null_value ||
                    minute < 0 || minute > 59 ||
                    second < 0 || second > 59 ||
-                   str->alloc(19))))
+                   str->alloc(MAX_DATE_STRING_REP_LENGTH))))
     return 0;
 
   bzero((char *)&ltime, sizeof(ltime));

sql/unireg.h

@@ -71,6 +71,7 @@
 #define MAX_TIME_WIDTH		23	/* -DDDDDD HH:MM:SS.###### */
 #define MAX_DATETIME_FULL_WIDTH 29	/* YYYY-MM-DD HH:MM:SS.###### AM */
 #define MAX_DATETIME_WIDTH	19	/* YYYY-MM-DD HH:MM:SS */
+#define MAX_DATETIME_COMPRESSED_WIDTH 14  /* YYYYMMDDHHMMSS */
 
 #define MAX_TABLES	(sizeof(table_map)*8-3)	/* Max tables in join */
 #define PARAM_TABLE_BIT	(((table_map) 1) << (sizeof(table_map)*8-3))