Bug #42064: low memory crash when importing hex strings, in

Item_hex_string::Item_hex_string

The status of memory allocation in the Lex_input_stream (called
from the Parser_state constructor) was not checked which led to
a parser crash in case of the out-of-memory error.

The solution is to introduce new init() member function in
Parser_state and Lex_input_stream so that status of memory
allocation can be returned to the caller.

mysql-test/r/error_simulation.result

@@ -39,5 +39,14 @@ a
 2
 DROP TABLE t1;
 #
+# Bug#42064: low memory crash when importing hex strings, in Item_hex_string::Item_hex_string
+#
+CREATE TABLE t1(a BLOB);
+SET SESSION debug="+d,bug42064_simulate_oom";
+INSERT INTO t1 VALUES("");
+Got one of the listed errors
+SET SESSION debug=DEFAULT;
+DROP TABLE t1;
+#
 # End of 5.1 tests
 #

mysql-test/t/error_simulation.test

@@ -46,6 +46,20 @@ SELECT * FROM t1;
 DROP TABLE t1;
 
 
+--echo #
+--echo # Bug#42064: low memory crash when importing hex strings, in Item_hex_string::Item_hex_string
+--echo #
+
+CREATE TABLE t1(a BLOB);
+
+SET SESSION debug="+d,bug42064_simulate_oom";
+# May fail with either ER_OUT_OF_RESOURCES or EE_OUTOFMEMORY
+--error ER_OUT_OF_RESOURCES, 5
+INSERT INTO t1 VALUES("");
+SET SESSION debug=DEFAULT;
+
+DROP TABLE t1;
+
 --echo #
 --echo # End of 5.1 tests
 --echo #

mysys/my_alloc.c

@@ -154,6 +154,14 @@ void *alloc_root(MEM_ROOT *mem_root, size_t length)
 
   DBUG_ASSERT(alloc_root_inited(mem_root));
 
+  DBUG_EXECUTE_IF("simulate_out_of_memory",
+                  {
+                    if (mem_root->error_handler)
+                      (*mem_root->error_handler)();
+                    DBUG_SET("-d,simulate_out_of_memory");
+                    DBUG_RETURN((void*) 0); /* purecov: inspected */
+                  });
+
   length+=ALIGN_SIZE(sizeof(USED_MEM));
   if (!(next = (USED_MEM*) my_malloc(length,MYF(MY_WME))))
   {
@@ -176,6 +184,14 @@ void *alloc_root(MEM_ROOT *mem_root, size_t length)
   DBUG_PRINT("enter",("root: 0x%lx", (long) mem_root));
   DBUG_ASSERT(alloc_root_inited(mem_root));
 
+  DBUG_EXECUTE_IF("simulate_out_of_memory",
+                  {
+                    /* Avoid reusing an already allocated block */
+                    if (mem_root->error_handler)
+                      (*mem_root->error_handler)();
+                    DBUG_SET("-d,simulate_out_of_memory");
+                    DBUG_RETURN((void*) 0); /* purecov: inspected */
+                  });
   length= ALIGN_SIZE(length);
   if ((*(prev= &mem_root->free)) != NULL)
   {

mysys/my_malloc.c

@@ -31,13 +31,23 @@ void *my_malloc(size_t size, myf my_flags)
 
   if (!size)
     size=1;					/* Safety */
-  if ((point = (char*)malloc(size)) == NULL)
+
+  point= (char *) malloc(size);
+  DBUG_EXECUTE_IF("simulate_out_of_memory",
+                  {
+                    free(point);
+                    point= NULL;
+                  });
+
+  if (point == NULL)
   {
     my_errno=errno;
     if (my_flags & MY_FAE)
       error_handler_hook=fatal_error_handler_hook;
     if (my_flags & (MY_FAE+MY_WME))
       my_error(EE_OUTOFMEMORY, MYF(ME_BELL+ME_WAITTANG+ME_NOREFRESH),size);
+    DBUG_EXECUTE_IF("simulate_out_of_memory",
+                    DBUG_SET("-d,simulate_out_of_memory"););
     if (my_flags & MY_FAE)
       exit(1);
   }

mysys/safemalloc.c

@@ -139,6 +139,11 @@ void *_mymalloc(size_t size, const char *filename, uint lineno, myf MyFlags)
 				     size +	/* size requested */
 				     4 +	/* overrun mark */
 				     sf_malloc_endhunc);
+    DBUG_EXECUTE_IF("simulate_out_of_memory",
+                    {
+                      free(irem);
+                      irem= NULL;
+                    });
   }
   /* Check if there isn't anymore memory avaiable */
   if (!irem)
@@ -159,6 +164,8 @@ void *_mymalloc(size_t size, const char *filename, uint lineno, myf MyFlags)
     }
     DBUG_PRINT("error",("Out of memory, in use: %ld at line %d, '%s'",
 			sf_malloc_max_memory,lineno, filename));
+    DBUG_EXECUTE_IF("simulate_out_of_memory",
+                    DBUG_SET("-d,simulate_out_of_memory"););
     if (MyFlags & MY_FAE)
       exit(1);
     DBUG_RETURN ((void*) 0);

sql/event_data_objects.cc

@@ -1433,7 +1433,10 @@ Event_job_data::execute(THD *thd, bool drop)
   thd->set_query(sp_sql.c_ptr_safe(), sp_sql.length());
 
   {
-    Parser_state parser_state(thd, thd->query(), thd->query_length());
+    Parser_state parser_state;
+    if (parser_state.init(thd, thd->query(), thd->query_length()))
+      goto end;
+
     lex_start(thd);
 
     if (parse_sql(thd, & parser_state, creation_ctx))

sql/mysqld.cc

@@ -2933,6 +2933,9 @@ int my_message_sql(uint error, const char *str, myf MyFlags)
       DBUG_RETURN(0);
     }
 
+    /* When simulating OOM, skip writing to error log to avoid mtr errors */
+    DBUG_EXECUTE_IF("simulate_out_of_memory", DBUG_RETURN(0););
+
     if (!thd->no_warnings_for_error &&
         !(MyFlags & ME_NO_WARNING_FOR_ERROR))
     {
@@ -2945,6 +2948,10 @@ int my_message_sql(uint error, const char *str, myf MyFlags)
       thd->no_warnings_for_error= FALSE;
     }
   }
+
+  /* When simulating OOM, skip writing to error log to avoid mtr errors */
+  DBUG_EXECUTE_IF("simulate_out_of_memory", DBUG_RETURN(0););
+
   if (!thd || MyFlags & ME_NOREFRESH)
     sql_print_error("%s: %s",my_progname,str); /* purecov: inspected */
   DBUG_RETURN(0);

sql/sp.cc

@@ -782,7 +782,12 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp,
   thd->spcont= NULL;
 
   {
-    Parser_state parser_state(thd, defstr.c_ptr(), defstr.length());
+    Parser_state parser_state;
+    if (parser_state.init(thd, defstr.c_ptr(), defstr.length()))
+    {
+      ret= SP_INTERNAL_ERROR;
+      goto end;
+    }
 
     lex_start(thd);
 

sql/sql_lex.cc

@@ -110,39 +110,31 @@ st_parsing_options::reset()
   allows_derived= TRUE;
 }
 
-Lex_input_stream::Lex_input_stream(THD *thd,
-                                   const char* buffer,
-                                   unsigned int length)
-: m_thd(thd),
-  yylineno(1),
-  yytoklen(0),
-  yylval(NULL),
-  m_ptr(buffer),
-  m_tok_start(NULL),
-  m_tok_end(NULL),
-  m_end_of_query(buffer + length),
-  m_tok_start_prev(NULL),
-  m_buf(buffer),
-  m_buf_length(length),
-  m_echo(TRUE),
-  m_cpp_tok_start(NULL),
-  m_cpp_tok_start_prev(NULL),
-  m_cpp_tok_end(NULL),
-  m_body_utf8(NULL),
-  m_cpp_utf8_processed_ptr(NULL),
-  next_state(MY_LEX_START),
-  found_semicolon(NULL),
-  ignore_space(test(thd->variables.sql_mode & MODE_IGNORE_SPACE)),
-  stmt_prepare_mode(FALSE),
-  in_comment(NO_COMMENT),
-  m_underscore_cs(NULL)
+
+bool Lex_input_stream::init(THD *thd, const char *buff, unsigned int length)
 {
+  DBUG_EXECUTE_IF("bug42064_simulate_oom",
+                  DBUG_SET("+d,simulate_out_of_memory"););
+
   m_cpp_buf= (char*) thd->alloc(length + 1);
+
+  DBUG_EXECUTE_IF("bug42064_simulate_oom",
+                  DBUG_SET("-d,bug42064_simulate_oom");); 
+
+  if (m_cpp_buf == NULL)
+    return FALSE;
+
   m_cpp_ptr= m_cpp_buf;
-}
+  m_thd= thd;
+  m_ptr= buff;
+  m_end_of_query= buff + length;
+  m_buf= buff;
+  m_buf_length= length;
+  ignore_space= test(thd->variables.sql_mode & MODE_IGNORE_SPACE);
+
+  return FALSE;
+  }
 
-Lex_input_stream::~Lex_input_stream()
-{}
 
 /**
   The operation is called from the parser in order to

sql/sql_lex.h

@@ -1147,9 +1147,38 @@ enum enum_comment_state
 class Lex_input_stream
 {
 public:
-  Lex_input_stream(THD *thd, const char* buff, unsigned int length);
-  ~Lex_input_stream();
+  Lex_input_stream() :
+    yylineno(1),
+    yytoklen(0),
+    yylval(NULL),
+    m_tok_start(NULL),
+    m_tok_end(NULL),
+    m_tok_start_prev(NULL),
+    m_echo(TRUE),
+    m_cpp_tok_start(NULL),
+    m_cpp_tok_start_prev(NULL),
+    m_cpp_tok_end(NULL),
+    m_body_utf8(NULL),
+    m_cpp_utf8_processed_ptr(NULL),
+    next_state(MY_LEX_START),
+    found_semicolon(NULL),
+    stmt_prepare_mode(FALSE),
+    in_comment(NO_COMMENT),
+    m_underscore_cs(NULL)
+  {
+  }
+
+  ~Lex_input_stream()
+  {
+  }
+
+  /**
+     Object initializer. Must be called before usage.
 
+     @retval FALSE OK
+     @retval TRUE  Error
+  */
+  bool init(THD *thd, const char *buff, unsigned int length);
   /**
     Set the echo mode.
 
@@ -1930,10 +1959,21 @@ public:
 class Parser_state
 {
 public:
-  Parser_state(THD *thd, const char* buff, unsigned int length)
-    : m_lip(thd, buff, length), m_yacc()
+  Parser_state()
+    : m_yacc()
   {}
 
+  /**
+     Object initializer. Must be called before usage.
+
+     @retval FALSE OK
+     @retval TRUE  Error
+  */
+  bool init(THD *thd, const char *buff, unsigned int length)
+  {
+    return m_lip.init(thd, buff, length);
+  }
+
   ~Parser_state()
   {}
 

sql/sql_parse.cc

@@ -5944,10 +5944,15 @@ void mysql_parse(THD *thd, const char *inBuf, uint length,
     sp_cache_flush_obsolete(&thd->sp_proc_cache);
     sp_cache_flush_obsolete(&thd->sp_func_cache);
 
-    Parser_state parser_state(thd, inBuf, length);
-
-    bool err= parse_sql(thd, & parser_state, NULL);
-    *found_semicolon= parser_state.m_lip.found_semicolon;
+    Parser_state parser_state;
+    bool err;
+    if (!(err= parser_state.init(thd, inBuf, length)))
+    {
+      err= parse_sql(thd, & parser_state, NULL);
+      *found_semicolon= parser_state.m_lip.found_semicolon;
+    }
+    else
+      *found_semicolon= NULL;
 
     if (!err)
     {
@@ -6033,14 +6038,17 @@ bool mysql_test_parse_for_slave(THD *thd, char *inBuf, uint length)
   bool error= 0;
   DBUG_ENTER("mysql_test_parse_for_slave");
 
-  Parser_state parser_state(thd, inBuf, length);
-  lex_start(thd);
-  mysql_reset_thd_for_next_command(thd);
+  Parser_state parser_state;
+  if (!(error= parser_state.init(thd, inBuf, length)))
+  {
+    lex_start(thd);
+    mysql_reset_thd_for_next_command(thd);
 
-  if (!parse_sql(thd, & parser_state, NULL) &&
-      all_tables_not_ok(thd,(TABLE_LIST*) lex->select_lex.table_list.first))
-    error= 1;                  /* Ignore question */
-  thd->end_statement();
+    if (!parse_sql(thd, & parser_state, NULL) &&
+        all_tables_not_ok(thd,(TABLE_LIST*) lex->select_lex.table_list.first))
+      error= 1;                  /* Ignore question */
+    thd->end_statement();
+  }
   thd->cleanup_after_query();
   DBUG_RETURN(error);
 }

sql/sql_partition.cc

@@ -3892,7 +3892,9 @@ bool mysql_unpack_partition(THD *thd,
   thd->lex= &lex;
   thd->variables.character_set_client= system_charset_info;
 
-  Parser_state parser_state(thd, part_buf, part_info_len);
+  Parser_state parser_state;
+  if (parser_state.init(thd, part_buf, part_info_len))
+    goto end;
 
   lex_start(thd);
   *work_part_info_used= false;

sql/sql_prepare.cc

@@ -3034,13 +3034,16 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
   old_stmt_arena= thd->stmt_arena;
   thd->stmt_arena= this;
 
-  Parser_state parser_state(thd, thd->query(), thd->query_length());
-  parser_state.m_lip.stmt_prepare_mode= TRUE;
-  lex_start(thd);
+  Parser_state parser_state;
+  if (!parser_state.init(thd, thd->query(), thd->query_length()))
+  {
+    parser_state.m_lip.stmt_prepare_mode= TRUE;
+    lex_start(thd);
 
-  error= parse_sql(thd, & parser_state, NULL) ||
-         thd->is_error() ||
-         init_param_array(this);
+    error= parse_sql(thd, & parser_state, NULL) ||
+      thd->is_error() ||
+      init_param_array(this);
+  }
 
   lex->set_trg_event_type_for_tables();
 

sql/sql_trigger.cc

@@ -1297,9 +1297,9 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
 
         thd->variables.sql_mode= (ulong)*trg_sql_mode;
 
-        Parser_state parser_state(thd,
-                                  trg_create_str->str,
-                                  trg_create_str->length);
+        Parser_state parser_state;
+        if (parser_state.init(thd, trg_create_str->str, trg_create_str->length))
+          goto err_with_lex_cleanup;
 
         Trigger_creation_ctx *creation_ctx=
           Trigger_creation_ctx::create(thd,

sql/sql_view.cc

@@ -1190,9 +1190,10 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
     char old_db_buf[NAME_LEN+1];
     LEX_STRING old_db= { old_db_buf, sizeof(old_db_buf) };
     bool dbchanged;
-    Parser_state parser_state(thd,
-                              table->select_stmt.str,
-                              table->select_stmt.length);
+    Parser_state parser_state;
+    if (parser_state.init(thd, table->select_stmt.str,
+                          table->select_stmt.length))
+        goto err;
 
     /* 
       Use view db name as thread default database, in order to ensure

sql/thr_malloc.cc

@@ -21,8 +21,6 @@
 extern "C" {
   void sql_alloc_error_handler(void)
   {
-    sql_print_error("%s", ER(ER_OUT_OF_RESOURCES));
-
     THD *thd= current_thd;
     if (thd)
     {
@@ -49,6 +47,12 @@ extern "C" {
                                       ER(ER_OUT_OF_RESOURCES));
       }
     }
+
+    /* Skip writing to the error log to avoid mtr complaints */
+    DBUG_EXECUTE_IF("simulate_out_of_memory", return;);
+
+    sql_print_error("%s", ER(ER_OUT_OF_RESOURCES));
+
   }
 }