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Bug #57130 crash in Item_field::print during SHOW CREATE TABLE or VIEW

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This crash could happen if SHOW CREATE VIEW indirectly failed to open a
view due to failures to open underlying tables (or functions). Several
such errors were hidden and converted to ER_VIEW_INVALID warnings to
prevent exposing details of underlying tables for which the user have
no privileges.

However, with the changes introduced by the patch for Bug#52044,
failing to open a view will cause opened tables, views and functions
to be closed. Since the errors causing these failures were converted
to warnings, SHOW CREATE VIEW would try to continue. This made it
possible to try to access memory that had been freed, causing a crash.

This patch fixes the problem by not closing opened tables, views and
functions in these cases. This allows SHOW CREATE VIEW to continue
and also prevents it from accessing freed memory.

Test case added to lock_sync.test.
This commit is contained in:
Jon Olav Hauglid
2010-11-03 16:47:32 +01:00
parent 70d86bd100
commit 0fb0d9a9a2
3 changed files with 105 additions and 2 deletions
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13
sql/sql_show.cc
View File

@ -29,6 +29,8 @@
#include "repl_failsafe.h"
#include "sql_parse.h" // check_access, check_table_access
#include "sql_partition.h" // partition_element
#include "sql_derived.h" // mysql_derived_prepare,
// mysql_handle_derived,
#include "sql_db.h" // check_db_dir_existence, load_db_opt_by_name
#include "sql_time.h" // interval_type_to_name
#include "tztime.h" // struct Time_zone
@ -683,11 +685,18 @@ mysqld_show_create(THD *thd, TABLE_LIST *table_list)
thd->lex->view_prepare_mode= TRUE;
{
/*
Use open_tables() directly rather than open_normal_and_derived_tables().
This ensures that close_thread_tables() is not called if open tables fails
and the error is ignored. This allows us to handle broken views nicely.
*/
uint counter;
Show_create_error_handler view_error_suppressor(thd, table_list);
thd->push_internal_handler(&view_error_suppressor);
bool open_error=
open_normal_and_derived_tables(thd, table_list,
MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL);
open_tables(thd, &table_list, &counter,
MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL) ||
mysql_handle_derived(thd->lex, &mysql_derived_prepare);
thd->pop_internal_handler();
if (open_error && (thd->killed || thd->is_error()))
goto exit;