Manual merge from mysql-5.1 for Bug#11764168 (56976: Severe denial

of service in prepared statements).

sql/sql_prepare.cc:
  At mysql_stmt_get_longdata(): instead of pushing an internal
  error handler (as done in 5.1-tree) we save, set and restore
  the statement's diagnostics area and warning info.

mysql-test/r/mysqld--help-notwin.result

@@ -309,6 +309,10 @@ The following options may be given as the first argument:
  max_join_size records return an error
  --max-length-for-sort-data=# 
  Max number of bytes in sorted records
+ --max-long-data-size=# 
+ The maximum BLOB length to send to server from
+ mysql_send_long_data API. Deprecated option; use
+ max_allowed_packet instead.
  --max-prepared-stmt-count=# 
  Maximum number of prepared statements in the server
  --max-relay-log-size=# 
@@ -830,6 +834,7 @@ max-error-count 64
 max-heap-table-size 16777216
 max-join-size 18446744073709551615
 max-length-for-sort-data 1024
+max-long-data-size 1048576
 max-prepared-stmt-count 16382
 max-relay-log-size 0
 max-seeks-for-key 18446744073709551615

mysql-test/r/mysqld--help-win.result

@@ -308,6 +308,10 @@ The following options may be given as the first argument:
  max_join_size records return an error
  --max-length-for-sort-data=# 
  Max number of bytes in sorted records
+ --max-long-data-size=# 
+ The maximum BLOB length to send to server from
+ mysql_send_long_data API. Deprecated option; use
+ max_allowed_packet instead.
  --max-prepared-stmt-count=# 
  Maximum number of prepared statements in the server
  --max-relay-log-size=# 
@@ -833,6 +837,7 @@ max-error-count 64
 max-heap-table-size 16777216
 max-join-size 18446744073709551615
 max-length-for-sort-data 1024
+max-long-data-size 1048576
 max-prepared-stmt-count 16382
 max-relay-log-size 0
 max-seeks-for-key 18446744073709551615

mysql-test/r/variables.result

@@ -1540,6 +1540,9 @@ ERROR HY000: Cannot drop default keycache
 SET @@global.key_cache_block_size=0;
 Warnings:
 Warning	1292	Truncated incorrect key_cache_block_size value: '0'
+select @@max_long_data_size;
+@@max_long_data_size
+1048576
 SET @@global.max_binlog_cache_size=DEFAULT;
 SET @@global.max_join_size=DEFAULT;
 SET @@global.key_buffer_size=@kbs;

mysql-test/suite/sys_vars/r/max_long_data_size_basic.result

+select @@global.max_long_data_size=20;
+@@global.max_long_data_size=20
+0
+select @@session.max_long_data_size;
+ERROR HY000: Variable 'max_long_data_size' is a GLOBAL variable
+SELECT @@global.max_long_data_size = VARIABLE_VALUE
+FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES
+WHERE VARIABLE_NAME='max_long_data_size';
+@@global.max_long_data_size = VARIABLE_VALUE
+1
+set global max_long_data_size=1;
+ERROR HY000: Variable 'max_long_data_size' is a read only variable
+set session max_long_data_size=1;
+ERROR HY000: Variable 'max_long_data_size' is a read only variable

mysql-test/suite/sys_vars/t/max_long_data_size_basic.test

+select @@global.max_long_data_size=20;
+--error ER_INCORRECT_GLOBAL_LOCAL_VAR
+select @@session.max_long_data_size;
+
+# Show that value of the variable matches the value in the GLOBAL I_S table
+SELECT @@global.max_long_data_size = VARIABLE_VALUE
+FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES
+WHERE VARIABLE_NAME='max_long_data_size';
+
+#
+# show that it's read-only
+#
+--error ER_INCORRECT_GLOBAL_LOCAL_VAR
+set global max_long_data_size=1;
+--error ER_INCORRECT_GLOBAL_LOCAL_VAR
+set session max_long_data_size=1;
+

mysql-test/t/variables.test

@@ -1281,6 +1281,11 @@ SET @@global.max_join_size=0;
 SET @@global.key_buffer_size=0;
 SET @@global.key_cache_block_size=0;
 
+#
+# Bug#56976: added new start-up parameter
+#
+select @@max_long_data_size;
+
 # cleanup
 SET @@global.max_binlog_cache_size=DEFAULT;
 SET @@global.max_join_size=DEFAULT;

sql/item.cc

@@ -2885,6 +2885,16 @@ bool Item_param::set_longdata(const char *str, ulong length)
     (here), and first have to concatenate all pieces together,
     write query to the binary log and only then perform conversion.
   */
+  if (str_value.length() + length > max_long_data_size)
+  {
+    my_message(ER_UNKNOWN_ERROR,
+               "Parameter of prepared statement which is set through "
+               "mysql_send_long_data() is longer than "
+               "'max_long_data_size' bytes",
+               MYF(0));
+    DBUG_RETURN(true);
+  }
+
   if (str_value.append(str, length, &my_charset_bin))
     DBUG_RETURN(TRUE);
   state= LONG_DATA_VALUE;

sql/mysqld.cc

@@ -324,6 +324,7 @@ static PSI_rwlock_key key_rwlock_openssl;
 
 /* the default log output is log tables */
 static bool lower_case_table_names_used= 0;
+static bool max_long_data_size_used= false;
 static bool volatile select_thread_in_use, signal_thread_in_use;
 /* See Bug#56666 and Bug#56760 */;
 volatile bool ready_to_exit;
@@ -478,6 +479,11 @@ ulong specialflag=0;
 ulong binlog_cache_use= 0, binlog_cache_disk_use= 0;
 ulong binlog_stmt_cache_use= 0, binlog_stmt_cache_disk_use= 0;
 ulong max_connections, max_connect_errors;
+/*
+  Maximum length of parameter value which can be set through
+  mysql_send_long_data() call.
+*/
+ulong max_long_data_size;
 /**
   Limit of the total number of prepared statements in the server.
   Is necessary to protect the server against out-of-memory attacks.
@@ -7160,6 +7166,10 @@ mysqld_get_one_option(int optid,
     if (argument == NULL) /* no argument */
       log_error_file_ptr= const_cast<char*>("");
     break;
+  case OPT_MAX_LONG_DATA_SIZE:
+    max_long_data_size_used= true;
+    WARN_DEPRECATED(NULL, 5, 6, "--max_long_data_size", "'--max_allowed_packet'");
+    break;
   }
   return 0;
 }
@@ -7386,6 +7396,13 @@ static int get_options(int *argc_ptr, char ***argv_ptr)
 
   opt_readonly= read_only;
 
+  /*
+    If max_long_data_size is not specified explicitly use
+    value of max_allowed_packet.
+  */
+  if (!max_long_data_size_used)
+    max_long_data_size= global_system_variables.max_allowed_packet;
+
   return 0;
 }
 

sql/mysqld.h

@@ -126,6 +126,7 @@ extern char *default_storage_engine;
 extern bool opt_endinfo, using_udf_functions;
 extern my_bool locked_in_memory;
 extern bool opt_using_transactions;
+extern ulong max_long_data_size;
 extern ulong current_pid;
 extern ulong expire_logs_days;
 extern my_bool relay_log_recovery;
@@ -397,7 +398,8 @@ enum options_mysqld
   OPT_UPDATE_LOG,
   OPT_WANT_CORE,
   OPT_ENGINE_CONDITION_PUSHDOWN,
-  OPT_LOG_ERROR
+  OPT_LOG_ERROR,
+  OPT_MAX_LONG_DATA_SIZE
 };
 
 

sql/sql_prepare.cc

@@ -2784,6 +2784,7 @@ void mysql_sql_stmt_close(THD *thd)
   }
 }
 
+
 /**
   Handle long data in pieces from client.
 
@@ -2840,16 +2841,25 @@ void mysql_stmt_get_longdata(THD *thd, char *packet, ulong packet_length)
 
   param= stmt->param_array[param_number];
 
+  Diagnostics_area new_stmt_da, *save_stmt_da= thd->stmt_da;
+  Warning_info new_warnning_info(thd->query_id), *save_warinig_info= thd->warning_info;
+
+  thd->stmt_da= &new_stmt_da;
+  thd->warning_info= &new_warnning_info;
+
 #ifndef EMBEDDED_LIBRARY
-  if (param->set_longdata(packet, (ulong) (packet_end - packet)))
+  param->set_longdata(packet, (ulong) (packet_end - packet));
 #else
-  if (param->set_longdata(thd->extra_data, thd->extra_length))
+  param->set_longdata(thd->extra_data, thd->extra_length);
 #endif
+  if (thd->stmt_da->is_error())
   {
     stmt->state= Query_arena::ERROR;
-    stmt->last_errno= ER_OUTOFMEMORY;
-    sprintf(stmt->last_error, ER(ER_OUTOFMEMORY), 0);
+    stmt->last_errno= thd->stmt_da->sql_errno();
+    strncpy(stmt->last_error, thd->stmt_da->message(), MYSQL_ERRMSG_SIZE);
   }
+  thd->stmt_da= save_stmt_da;
+  thd->warning_info= save_warinig_info;
 
   general_log_print(thd, thd->command, NullS);
 
@@ -3389,6 +3399,13 @@ Prepared_statement::execute_loop(String *expanded_query,
   bool error;
   int reprepare_attempt= 0;
 
+  /* Check if we got an error when sending long data */
+  if (state == Query_arena::ERROR)
+  {
+    my_message(last_errno, last_error, MYF(0));
+    return TRUE;
+  }
+
   if (set_parameters(expanded_query, packet, packet_end))
     return TRUE;
 
@@ -3656,12 +3673,6 @@ bool Prepared_statement::execute(String *expanded_query, bool open_cursor)
 
   status_var_increment(thd->status_var.com_stmt_execute);
 
-  /* Check if we got an error when sending long data */
-  if (state == Query_arena::ERROR)
-  {
-    my_message(last_errno, last_error, MYF(0));
-    return TRUE;
-  }
   if (flags & (uint) IS_IN_USE)
   {
     my_error(ER_PS_NO_RECURSION, MYF(0));

sql/sys_vars.cc

@@ -1182,6 +1182,16 @@ static Sys_var_harows Sys_sql_max_join_size(
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0),
        ON_UPDATE(fix_max_join_size), DEPRECATED(70000, 0));
 
+static Sys_var_ulong Sys_max_long_data_size(
+       "max_long_data_size",
+       "The maximum BLOB length to send to server from "
+       "mysql_send_long_data API. Deprecated option; "
+       "use max_allowed_packet instead.",
+       READ_ONLY GLOBAL_VAR(max_long_data_size),
+       CMD_LINE(REQUIRED_ARG, OPT_MAX_LONG_DATA_SIZE),
+       VALID_RANGE(1024, UINT_MAX32), DEFAULT(1024*1024),
+       BLOCK_SIZE(1));
+
 static PolyLock_mutex PLock_prepared_stmt_count(&LOCK_prepared_stmt_count);
 static Sys_var_ulong Sys_max_prepared_stmt_count(
        "max_prepared_stmt_count",

tests/mysql_client_test.c

@@ -19464,6 +19464,56 @@ static void test_bug49972()
 }
 
 
+/*
+  Bug #56976:   Severe Denial Of Service in prepared statements
+*/
+static void test_bug56976()
+{
+  MYSQL_STMT   *stmt;
+  MYSQL_BIND    bind[1];
+  int           rc;
+  const char*   query = "SELECT LENGTH(?)";
+  char *long_buffer;
+  unsigned long i, packet_len = 256 * 1024L;
+  unsigned long dos_len    = 2 * 1024 * 1024L;
+
+  DBUG_ENTER("test_bug56976");
+  myheader("test_bug56976");
+
+  stmt= mysql_stmt_init(mysql);
+  check_stmt(stmt);
+
+  rc= mysql_stmt_prepare(stmt, query, strlen(query));
+  check_execute(stmt, rc);
+
+  memset(bind, 0, sizeof(bind));
+  bind[0].buffer_type = MYSQL_TYPE_TINY_BLOB;
+
+  rc= mysql_stmt_bind_param(stmt, bind);
+  check_execute(stmt, rc);
+
+  long_buffer= (char*) my_malloc(packet_len, MYF(0));
+  DIE_UNLESS(long_buffer);
+
+  memset(long_buffer, 'a', packet_len);
+
+  for (i= 0; i < dos_len / packet_len; i++)
+  {
+    rc= mysql_stmt_send_long_data(stmt, 0, long_buffer, packet_len);
+    check_execute(stmt, rc);
+  }
+
+  my_free(long_buffer);
+  rc= mysql_stmt_execute(stmt);
+
+  DIE_UNLESS(rc && mysql_stmt_errno(stmt) == ER_UNKNOWN_ERROR);
+
+  mysql_stmt_close(stmt);
+
+  DBUG_VOID_RETURN;
+}
+
+
 /**
   Bug#57058 SERVER_QUERY_WAS_SLOW not wired up.
 */
@@ -19838,6 +19888,7 @@ static struct my_tests_st my_tests[]= {
   { "test_bug47485", test_bug47485 },
   { "test_bug58036", test_bug58036 },
   { "test_bug57058", test_bug57058 },
+  { "test_bug56976", test_bug56976 },
   { 0, 0 }
 };