Bug#34043: Server loops excessively in _checkchunk() when safemalloc is enabled

Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.

Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.

Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost. 

The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.

Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.

1 files changed, 54 insertions, 56 deletions

diff --git a/sql-common/client.c b/sql-common/client.c
index bb7bd4d2633..c277b153109 100644
--- a/sql-common/client.c
+++ b/sql-common/client.c
@@ -688,8 +688,7 @@ err2:
       CloseHandle(handle_file_map);
   }
 err:
-  if (tmp)
-    my_free(tmp, MYF(0));
+  my_free(tmp);
   if (error_allow)
     error_code = GetLastError();
   if (event_connect_request)
@@ -802,7 +801,7 @@ void free_rows(MYSQL_DATA *cur)
   if (cur)
   {
     free_root(&cur->alloc,MYF(0));
-    my_free((uchar*) cur,MYF(0));
+    my_free(cur);
   }
 }
 
@@ -1127,9 +1126,8 @@ mysql_free_result(MYSQL_RES *result)
     free_rows(result->data);
     if (result->fields)
       free_root(&result->field_alloc,MYF(0));
-    if (result->row)
-      my_free((uchar*) result->row,MYF(0));
-    my_free((uchar*) result,MYF(0));
+    my_free(result->row);
+    my_free(result);
   }
   DBUG_VOID_RETURN;
 }
@@ -1167,13 +1165,13 @@ static int add_init_command(struct st_mysql_options *options, const char *cmd)
   {
     options->init_commands= (DYNAMIC_ARRAY*)my_malloc(sizeof(DYNAMIC_ARRAY),
 						      MYF(MY_WME));
-    init_dynamic_array(options->init_commands,sizeof(char*),0,5 CALLER_INFO);
+    init_dynamic_array(options->init_commands,sizeof(char*),0,5);
   }
 
   if (!(tmp= my_strdup(cmd,MYF(MY_WME))) ||
       insert_dynamic(options->init_commands, (uchar*)&tmp))
   {
-    my_free(tmp, MYF(MY_ALLOW_ZERO_PTR));
+    my_free(tmp);
     return 1;
   }
 
@@ -1221,7 +1219,7 @@ void mysql_read_default_options(struct st_mysql_options *options,
 	case 2:				/* socket */
 	  if (opt_arg)
 	  {
-	    my_free(options->unix_socket,MYF(MY_ALLOW_ZERO_PTR));
+	    my_free(options->unix_socket);
 	    options->unix_socket=my_strdup(opt_arg,MYF(MY_WME));
 	  }
 	  break;
@@ -1232,7 +1230,7 @@ void mysql_read_default_options(struct st_mysql_options *options,
 	case 4:				/* password */
 	  if (opt_arg)
 	  {
-	    my_free(options->password,MYF(MY_ALLOW_ZERO_PTR));
+	    my_free(options->password);
 	    options->password=my_strdup(opt_arg,MYF(MY_WME));
 	  }
 	  break;
@@ -1246,7 +1244,7 @@ void mysql_read_default_options(struct st_mysql_options *options,
 	case 7:				/* user */
 	  if (opt_arg)
 	  {
-	    my_free(options->user,MYF(MY_ALLOW_ZERO_PTR));
+	    my_free(options->user);
 	    options->user=my_strdup(opt_arg,MYF(MY_WME));
 	  }
 	  break;
@@ -1256,14 +1254,14 @@ void mysql_read_default_options(struct st_mysql_options *options,
 	case 9:				/* host */
 	  if (opt_arg)
 	  {
-	    my_free(options->host,MYF(MY_ALLOW_ZERO_PTR));
+	    my_free(options->host);
 	    options->host=my_strdup(opt_arg,MYF(MY_WME));
 	  }
 	  break;
 	case 10:			/* database */
 	  if (opt_arg)
 	  {
-	    my_free(options->db,MYF(MY_ALLOW_ZERO_PTR));
+	    my_free(options->db);
 	    options->db=my_strdup(opt_arg,MYF(MY_WME));
 	  }
 	  break;
@@ -1277,23 +1275,23 @@ void mysql_read_default_options(struct st_mysql_options *options,
 	  break;
 #if defined(HAVE_OPENSSL) && !defined(EMBEDDED_LIBRARY)
 	case 13:			/* ssl_key */
-	  my_free(options->ssl_key, MYF(MY_ALLOW_ZERO_PTR));
+	  my_free(options->ssl_key);
           options->ssl_key = my_strdup(opt_arg, MYF(MY_WME));
           break;
 	case 14:			/* ssl_cert */
-	  my_free(options->ssl_cert, MYF(MY_ALLOW_ZERO_PTR));
+	  my_free(options->ssl_cert);
           options->ssl_cert = my_strdup(opt_arg, MYF(MY_WME));
           break;
 	case 15:			/* ssl_ca */
-	  my_free(options->ssl_ca, MYF(MY_ALLOW_ZERO_PTR));
+	  my_free(options->ssl_ca);
           options->ssl_ca = my_strdup(opt_arg, MYF(MY_WME));
           break;
 	case 16:			/* ssl_capath */
-	  my_free(options->ssl_capath, MYF(MY_ALLOW_ZERO_PTR));
+	  my_free(options->ssl_capath);
           options->ssl_capath = my_strdup(opt_arg, MYF(MY_WME));
           break;
         case 23:			/* ssl_cipher */
-          my_free(options->ssl_cipher, MYF(MY_ALLOW_ZERO_PTR));
+          my_free(options->ssl_cipher);
           options->ssl_cipher= my_strdup(opt_arg, MYF(MY_WME));
           break;
 #else
@@ -1305,11 +1303,11 @@ void mysql_read_default_options(struct st_mysql_options *options,
 	  break;
 #endif /* HAVE_OPENSSL && !EMBEDDED_LIBRARY */
 	case 17:			/* charset-lib */
-	  my_free(options->charset_dir,MYF(MY_ALLOW_ZERO_PTR));
+	  my_free(options->charset_dir);
           options->charset_dir = my_strdup(opt_arg, MYF(MY_WME));
 	  break;
 	case 18:
-	  my_free(options->charset_name,MYF(MY_ALLOW_ZERO_PTR));
+	  my_free(options->charset_name);
           options->charset_name = my_strdup(opt_arg, MYF(MY_WME));
 	  break;
 	case 19:				/* Interactive-timeout */
@@ -1339,7 +1337,7 @@ void mysql_read_default_options(struct st_mysql_options *options,
         case 26: /* shared_memory_base_name */
 #ifdef HAVE_SMEM
           if (options->shared_memory_base_name != def_shared_memory_base_name)
-            my_free(options->shared_memory_base_name,MYF(MY_ALLOW_ZERO_PTR));
+            my_free(options->shared_memory_base_name);
           options->shared_memory_base_name=my_strdup(opt_arg,MYF(MY_WME));
 #endif
           break;
@@ -1760,14 +1758,14 @@ mysql_ssl_free(MYSQL *mysql __attribute__((unused)))
   struct st_VioSSLFd *ssl_fd= (struct st_VioSSLFd*) mysql->connector_fd;
   DBUG_ENTER("mysql_ssl_free");
 
-  my_free(mysql->options.ssl_key, MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.ssl_cert, MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.ssl_ca, MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.ssl_capath, MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.ssl_cipher, MYF(MY_ALLOW_ZERO_PTR));
+  my_free(mysql->options.ssl_key);
+  my_free(mysql->options.ssl_cert);
+  my_free(mysql->options.ssl_ca);
+  my_free(mysql->options.ssl_capath);
+  my_free(mysql->options.ssl_cipher);
   if (ssl_fd)
     SSL_CTX_free(ssl_fd->ssl_context);
-  my_free(mysql->connector_fd,MYF(MY_ALLOW_ZERO_PTR));
+  my_free(mysql->connector_fd);
   mysql->options.ssl_key = 0;
   mysql->options.ssl_cert = 0;
   mysql->options.ssl_ca = 0;
@@ -2271,8 +2269,8 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
 			       (mysql->options.my_cnf_file ?
 				mysql->options.my_cnf_file : "my"),
 			       mysql->options.my_cnf_group);
-    my_free(mysql->options.my_cnf_file,MYF(MY_ALLOW_ZERO_PTR));
-    my_free(mysql->options.my_cnf_group,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->options.my_cnf_file);
+    my_free(mysql->options.my_cnf_group);
     mysql->options.my_cnf_file=mysql->options.my_cnf_group=0;
   }
 
@@ -3014,7 +3012,7 @@ mysql_select_db(MYSQL *mysql, const char *db)
   if ((error=simple_command(mysql,COM_INIT_DB, (const uchar*) db,
                             (ulong) strlen(db),0)))
     DBUG_RETURN(error);
-  my_free(mysql->db,MYF(MY_ALLOW_ZERO_PTR));
+  my_free(mysql->db);
   mysql->db=my_strdup(db,MYF(MY_WME));
   DBUG_RETURN(0);
 }
@@ -3029,32 +3027,32 @@ static void mysql_close_free_options(MYSQL *mysql)
 {
   DBUG_ENTER("mysql_close_free_options");
 
-  my_free(mysql->options.user,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.host,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.password,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.unix_socket,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.db,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.my_cnf_file,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.my_cnf_group,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.charset_dir,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.charset_name,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->options.client_ip,MYF(MY_ALLOW_ZERO_PTR));
+  my_free(mysql->options.user);
+  my_free(mysql->options.host);
+  my_free(mysql->options.password);
+  my_free(mysql->options.unix_socket);
+  my_free(mysql->options.db);
+  my_free(mysql->options.my_cnf_file);
+  my_free(mysql->options.my_cnf_group);
+  my_free(mysql->options.charset_dir);
+  my_free(mysql->options.charset_name);
+  my_free(mysql->options.client_ip);
   if (mysql->options.init_commands)
   {
     DYNAMIC_ARRAY *init_commands= mysql->options.init_commands;
     char **ptr= (char**)init_commands->buffer;
     char **end= ptr + init_commands->elements;
     for (; ptr<end; ptr++)
-      my_free(*ptr,MYF(MY_WME));
+      my_free(*ptr);
     delete_dynamic(init_commands);
-    my_free((char*)init_commands,MYF(MY_WME));
+    my_free(init_commands);
   }
 #if defined(HAVE_OPENSSL) && !defined(EMBEDDED_LIBRARY)
   mysql_ssl_free(mysql);
 #endif /* HAVE_OPENSSL && !EMBEDDED_LIBRARY */
 #ifdef HAVE_SMEM
   if (mysql->options.shared_memory_base_name != def_shared_memory_base_name)
-    my_free(mysql->options.shared_memory_base_name,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->options.shared_memory_base_name);
 #endif /* HAVE_SMEM */
   bzero((char*) &mysql->options,sizeof(mysql->options));
   DBUG_VOID_RETURN;
@@ -3063,12 +3061,12 @@ static void mysql_close_free_options(MYSQL *mysql)
 
 static void mysql_close_free(MYSQL *mysql)
 {
-  my_free((uchar*) mysql->host_info,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->user,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->passwd,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->db,MYF(MY_ALLOW_ZERO_PTR));
+  my_free(mysql->host_info);
+  my_free(mysql->user);
+  my_free(mysql->passwd);
+  my_free(mysql->db);
 #if defined(EMBEDDED_LIBRARY) || MYSQL_VERSION_ID >= 50100
-  my_free(mysql->info_buffer,MYF(MY_ALLOW_ZERO_PTR));
+  my_free(mysql->info_buffer);
   mysql->info_buffer= 0;
 #endif
   /* Clear pointers for better safety */
@@ -3176,7 +3174,7 @@ void STDCALL mysql_close(MYSQL *mysql)
       (*mysql->methods->free_embedded_thd)(mysql);
 #endif
     if (mysql->free_me)
-      my_free((uchar*) mysql,MYF(0));
+      my_free(mysql);
   }
   DBUG_VOID_RETURN;
 }
@@ -3313,7 +3311,7 @@ MYSQL_RES * STDCALL mysql_store_result(MYSQL *mysql)
   if (!(result->data=
 	(*mysql->methods->read_rows)(mysql,mysql->fields,mysql->field_count)))
   {
-    my_free((uchar*) result,MYF(0));
+    my_free(result);
     DBUG_RETURN(0);
   }
   mysql->affected_rows= result->row_count= result->data->rows;
@@ -3361,7 +3359,7 @@ static MYSQL_RES * cli_use_result(MYSQL *mysql)
   if (!(result->row=(MYSQL_ROW)
 	my_malloc(sizeof(result->row[0])*(mysql->field_count+1), MYF(MY_WME))))
   {					/* Ptrs: to one row */
-    my_free((uchar*) result,MYF(0));
+    my_free(result);
     DBUG_RETURN(0);
   }
   result->fields=	mysql->fields;
@@ -3482,19 +3480,19 @@ mysql_options(MYSQL *mysql,enum mysql_option option, const void *arg)
     add_init_command(&mysql->options,arg);
     break;
   case MYSQL_READ_DEFAULT_FILE:
-    my_free(mysql->options.my_cnf_file,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->options.my_cnf_file);
     mysql->options.my_cnf_file=my_strdup(arg,MYF(MY_WME));
     break;
   case MYSQL_READ_DEFAULT_GROUP:
-    my_free(mysql->options.my_cnf_group,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->options.my_cnf_group);
     mysql->options.my_cnf_group=my_strdup(arg,MYF(MY_WME));
     break;
   case MYSQL_SET_CHARSET_DIR:
-    my_free(mysql->options.charset_dir,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->options.charset_dir);
     mysql->options.charset_dir=my_strdup(arg,MYF(MY_WME));
     break;
   case MYSQL_SET_CHARSET_NAME:
-    my_free(mysql->options.charset_name,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->options.charset_name);
     mysql->options.charset_name=my_strdup(arg,MYF(MY_WME));
     break;
   case MYSQL_OPT_PROTOCOL:
@@ -3503,7 +3501,7 @@ mysql_options(MYSQL *mysql,enum mysql_option option, const void *arg)
   case MYSQL_SHARED_MEMORY_BASE_NAME:
 #ifdef HAVE_SMEM
     if (mysql->options.shared_memory_base_name != def_shared_memory_base_name)
-      my_free(mysql->options.shared_memory_base_name,MYF(MY_ALLOW_ZERO_PTR));
+      my_free(mysql->options.shared_memory_base_name);
     mysql->options.shared_memory_base_name=my_strdup(arg,MYF(MY_WME));
 #endif
     break;