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BUG#23509275 :DBUG_PRINT in THD::decide_logging_format prints incorrectly, access out-of-bound

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Problem:
In debug builds, there is a chance that an out-of-bounds
read is performed when tables are locked in
LTM_PRELOCKED_UNDER_LOCK_TABLES mode. It can happen because
the debug code uses enum values as index for an array of
mode descriptions, but it only takes into consideration 3
out of 4 of the enum values.

Fix:
This patch fixes it by implementing a getter for the enum which
returns a string representation of the enum,
effectively removing the out-of-bounds read.

Moreover, it also fixes the lock mode descriptions that
would be print out in debug builds.
This commit is contained in:
Neha Kumari
2016-07-25 20:34:20 +05:30
parent 2674cf91c5
commit a63a250d40
2 changed files with 33 additions and 10 deletions
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32
sql/sql_class.cc
View File

@ -1,5 +1,5 @@
/*
Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -4246,6 +4246,25 @@ has_write_table_auto_increment_not_first_in_pk(TABLE_LIST *tables)
return 0;
}
#ifndef DBUG_OFF
const char * get_locked_tables_mode_name(enum_locked_tables_mode locked_tables_mode)
{
switch (locked_tables_mode)
{
case LTM_NONE:
return "LTM_NONE";
case LTM_LOCK_TABLES:
return "LTM_LOCK_TABLES";
case LTM_PRELOCKED:
return "LTM_PRELOCKED";
case LTM_PRELOCKED_UNDER_LOCK_TABLES:
return "LTM_PRELOCKED_UNDER_LOCK_TABLES";
default:
return "Unknown table lock mode";
}
}
#endif
/**
Decide on logging format to use for the statement and issue errors
or warnings as needed. The decision depends on the following
@ -4397,15 +4416,8 @@ int THD::decide_logging_format(TABLE_LIST *tables)
TABLE* prev_access_table= NULL;
#ifndef DBUG_OFF
{
static const char *prelocked_mode_name[] = {
"NON_PRELOCKED",
"PRELOCKED",
"PRELOCKED_UNDER_LOCK_TABLES",
};
DBUG_PRINT("debug", ("prelocked_mode: %s",
prelocked_mode_name[locked_tables_mode]));
}
DBUG_PRINT("debug", ("prelocked_mode: %s",
get_locked_tables_mode_name(locked_tables_mode)));
#endif
if (variables.binlog_format != BINLOG_FORMAT_ROW && tables)

11
sql/sql_class.h
View File

@ -963,6 +963,8 @@ typedef I_List<Item_change_record> Item_change_list;
/**
Type of locked tables mode.
See comment for THD::locked_tables_mode for complete description.
While adding new enum values add them to the getter method for this enum
declared below and defined in sql_class.cc as well.
*/
enum enum_locked_tables_mode
@ -973,6 +975,15 @@ enum enum_locked_tables_mode
LTM_PRELOCKED_UNDER_LOCK_TABLES
};
#ifndef DBUG_OFF
/**
Getter for the enum enum_locked_tables_mode
@param locked_tables_mode enum for types of locked tables mode
@return The string represantation of that enum value
*/
const char * get_locked_tables_mode_name(enum_locked_tables_mode locked_tables_mode);
#endif
/**
Class that holds information about tables which were opened and locked