WITH MALFORMED XPATH EXP
Problem:
A malformed XPATH expression in the ExtractValue query is 
causing a server crash. This malformed XPATH expression is
resulted when the position attribute in the substring function
contains ".." in the beginning.
Solution:
The original crash is happening because the "../" is being 
evaluated prematurely. It tries to access XML while it 
hasn't been parsed yet. The premature evaluation is happening
because the val_nodeset function is being set to constant, 
in which case we proceed to evaluate them in JOIN:prepare
stage only. The solution to this is setting the val_nodeset
functions as non-constant. This forces us to evaluate the function
 in the JOIN:exec stage and thus avoid any premature evaluation of
the XML strings.

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get_cost_calc_buff_size() could return wrong value for the size of imerge_cost_buff.

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    UPPER CASE HOST NAME ANYMORE

Description:
It is not possible to drop users with host names with upper case
letters in them. i.e DROP USER 'root'@'Tmp_Host_Name'; is failing
with error.

Analysis: Since the fix 11748570 we came up with lower case hostnames
as standard. But in the current bug the hostname is created by
mysql_install_db script is still having upper case hostnames. 
So, if we have the hostname with upper case letters like(Tmp_Host_Name)
then we will have as it is stored in the mysql.user table. 
In this case if use "'DROP USER 'root'@'Tmp_Host_Name';" it gives 
error because we do compare with the lower case of hostname since the 
11748570 fix.

Fix: We need to convert the hostname to lower case before storing into 
the mysql.user table when we run the mysql_install_db script.

The filesort implementation needs space for at least 15 records
(plus some internal overhead) in its main sort buffer.

             AS A INNODB PARTITTION.

PROBLEM
-------
The correct engine_type was not being set during 
rebuild of the partition due to which the handler
was always created with the default engine,
which is innodb for 5.5+ ,therefore even if the
table was myisam, after rebuilding the partitions
ended up as innodb partitions.

FIX
---
Set the correct engine type during rebuild.  

[Approved by mattiasj #rb3599]

REPLICATION FILTERS ARE USED.

Problem:
When Filtered-slave applies Int_var_log_event and when it
tries to write the event to its own binlog, LAST_INSERT_ID
value is written wrongly.

Analysis:
THD::stmt_depends_on_first_successful_insert_id_in_prev_stmt
is a variable which is set when LAST_INSERT_ID() is used by
a statement. If it is set, first_successful_insert_id_in_
prev_stmt_for_binlog will be stored in the statement-based
binlog. This variable is CUMULATIVE along the execution of
a stored function or trigger: if one substatement sets it
to 1 it will stay 1 until the function/trigger ends,
thus making sure that first_successful_insert_id_in_
prev_stmt_for_binlog does not change anymore and is
propagated to the caller for binlogging. This is achieved
using the following code
if(!stmt_depends_on_first_successful_insert_id_in_prev_stmt)               
{                                                                           
  /* It's the first time we read it */                                      
  first_successful_insert_id_in_prev_stmt_for_binlog=                       
  first_successful_insert_id_in_prev_stmt;                                
  stmt_depends_on_first_successful_insert_id_in_prev_stmt= 1;               
}

Slave server, after receiving Int_var_log_event event from
master, it is setting
stmt_depends_on_first_successful_insert_id_in_prev_stmt
to true(*which is wrong*) and not setting
first_successful_insert_id_in_prev_stmt_for_binlog. Because
of this problem, when the actual DML statement with
LAST_INSERT_ID() is parsed by slave SQL thread,
first_successful_insert_id_in_prev_stmt_for_binlog is not
set. Hence the value zero (default value) is written to
slave's binlog.

Why only *Filtered slave* is effected when the code is
in common place:
-------------------------------------------------------
In Query_log_event::do_apply_event,
THD::stmt_depends_on_first_successful_insert_id_in_prev_stmt
is reset to zero at the end of the function. In case of
normal slave (No Filters), this variable will be reset. 
In Filtered slave, Slave SQL thread defers all IRU events's
execution until IRU's Query_log event is received. Once it
receives Query_log_event it executes all pending IRU events
and then it executes Query_log_event. Hence the variable is
not getting reset to 0, causing this bug.

Fix: As described above, the root cause was setting 
THD::stmt_depends_on_first_successful_insert_id_in_prev_stmt
when Int_var_log_event was executed by a SQL thread. Hence
removing the problematic line from the code.

Description: Fix for bug CVE-2012-5611 (bug 67685) is 
incomplete. The ACL_KEY_LENGTH-sized buffers in acl_get() and 
check_grant_db() can be overflown by up to two bytes. That's 
probably not enough to do anything more serious than crashing 
mysqld.
Analysis: In acl_get() when "copy_length" is calculated it 
just adding the variable lengths. But when we are using them 
with strmov() we are adding +1 to each. This will lead to a 
three byte buffer overflow (i.e two +1's at strmov() and one 
byte for the null added by strmov() function). Similarly it 
happens for check_grant_db() function as well.
Fix: We need to add "+2" to "copy_length" in acl_get() 
and "+1" to "copy_length" in check_grant_db(). 

WL#7266: Dump-thread additional concurrency tests                                                                                                                           

This worklog aims at testing the two following scenarios:

1) Whenever the mysql_binlog_send method (dump thread)
reaches the end of file when reading events from the binlog, before
checking if it should wait for more events, there was a test to
check if the file being read was still active, i.e, it was the last
known binlog. However, it was possible that something was written to
the binary log and then a rotation would happen, after EOF was
detected and before the check for active was performed. In this
case, the end of the binary log would not be read by the dump
thread, and this would cause the slave to lose updates.
This test verifies that the problem has been fixed. It waits during
this window while forcing a rotation in the binlog.

2) Verify dump thread can send events in active file, correctly after
encountering an IO error.

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ha_innobase::records_in_range() should return HA_POS_ERROR for the table during discarded without requesting pages.
The later other handler method should treat the error correctly.

Approved by Sunny in rb#3433

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disable testcase due to BUG#17446090

	       IT IS DONE IN-PLACE

With change buffer enabled, InnoDB doesn't write a transaction log
record when it merges a record from the insert buffer to an secondary
index page if the insertion is performed as an update-in-place.

Fixed by logging the 'update-in-place' operation on secondary index
pages.

Approved by Marko. rb#2429

                WITH MY_B_VPRINTF()
Issue         : In LP 64 machine max long value can be 20 digit
                decimal value. But in my_b_vprintf() the intermediate
                buffer storage used is 17 bytes length. This will lead to
                buffer overflow.
Solution      : Increased the buffer storage from 17 to 32 bytes.
                code is backported from 5.6


mysys/mf_iocache2.c:
  In function my_b_vprintf increased the size of local buff from 17 to
  32 bytes.

Postfix, suppress the new warning generated by the bug's fix.

Dump thread may encounter an error when reading events from the active binlog
file. However the errors may be temporary, so dump thread will try to read
the event again. But dump thread seeked to an wrong position, it caused some
events was sent twice.

To fix the bug, prev_pos is defined out the while loop and is set the correct
position after reading every event correctly.

This patch also make binlog_can_be_corrupted more accurate, only the binlogs
not closed normally are marked binlog_can_be_corrupted.

Finally, two warnings are added when dump threads encounter the temporary
errors.

 Reverted the changes to spec file to ignore mysqld_safe.pid file, updated the logic to get the correct count of PID files

      
Reverting the patch. Because this change is not to me made for GA versions.

Memory Leak in mysql_options() was caused by missing call
to my_free() in MYSQL_SET_CLIENT_IP branch. Fixed by adding
my_free() to cleanup mysql->options.client_ip value before
assigning new value.

             ERROR HANDLING CODE 

BACKGROUND:
There can be a potential crash due to buffer overrun in 
SSL error handling code due to missing comma in
ssl_error_string[] array in viosslfactories.c.

ANALYSIS:
Found by code Inspection.

FIX:
Added the missing comma in SSL error handling code
in ssl_error_string[] array in viosslfactories.c.

Problem:-
In a Procedure, when we are comparing value of select query 
with IN clause and they both have different collation, cause 
error on first time execution and assert second time.
procedure will have query like
set @x = ((select a from t1) in (select d from t2));<---proc1
              sel1                   sel2

Analysis:-
When we execute this proc1(first time)
While resolving the fields of user variable, we will call 
Item_in_subselect::fix_fields while will resolve sel2. There 
in Item_in_subselect::select_transformer, we evaluate the 
left expression(sel1) and store it in Item_cache_* object 
(to avoid re-evaluating it many times during subquery execution) 
by making Item_in_optimizer class.
While evaluating left expression we will prepare sel1.
After that, we will put a new condition in sel2  
in Item_in_subselect::select_transformer() which will compare 
t2.d and sel1(which is cached in Item_in_optimizer).

Later while checking the collation in agg_item_collations() 
we get error and we cleanup the item. While cleaning up we cleaned 
the cached value in Item_in_optimizer object.

When we execute the procedure second time, we have condition for 
sel2 and while setup_cond(), we can't able to find reference item 
as it is cleanup while item cleanup.So it assert.


Solution:-
We should not cleanup the cached value for Item_in_optimizer object, 
if we have put the condition to subselect.

compressed pages

After loading a compressed-only page in buf_page_get_gen() we allocate a new
block for decompression. The problem is that the compressed page is neither
buffer-fixed nor I/O-fixed by the time we call buf_LRU_get_free_block(),
so it may end up being evicted and returned back as a new block.

buf_page_get_gen(): Temporarily buffer-fix the compressed-only block
while allocating memory for an uncompressed page frame.
This should prevent this form of the infinite loop, which is more likely
with a small innodb_buffer_pool_size.

rb#2511 approved by Jimmy Yang, Sunny Bains

               "SHOW PROCESSLIST"

Analysis:
----------
The problem here is, if one connection changes its
default db and at the same time another connection executes
"SHOW PROCESSLIST", when it wants to read db of the another
connection then there is a chance of accessing the invalid
memory. 

The db name stored in THD is not guarded while changing user
DB and while reading the user DB in "SHOW PROCESSLIST".
So, if THD.db is freed by thd "owner" thread and if another
thread executing "SHOW PROCESSLIST" statement tries to read
and copy THD.db at the same time then we may endup in the issue
reported here.

Fix:
----------
Used mutex "LOCK_thd_data" to guard THD.db while freeing it
and while copying it to processlist.

DICT_TABLE_GET_FORMAT(CLUST_INDEX->TABLE) >= 1

The function row_sel_sec_rec_is_for_clust_rec() was incorrectly
preparing to compare a NULL column prefix in a secondary index with a
non-NULL column in a clustered index.

This can trigger an assertion failure in 5.1 plugin and later. In the
built-in InnoDB of MySQL 5.1 and earlier, we would apparently only do
some extra work, by trimming the clustered index field for the
comparison.

The code might actually have worked properly apart from this debug
assertion failure. It is merely doing some extra work in fetching a
BLOB column, and then comparing it to NULL (which would return the
same result, no matter what the BLOB contents is).

While the test case involves CHECK TABLE, this could theoretically
occur during any read that uses a secondary index on a column prefix
of a column that can be NULL.

rb#3101 approved by Mattias Jonsson

There was a race condition in the rollback of TRX_UNDO_UPD_DEL_REC.

Once row_undo_mod_clust() has rolled back the changes by the rolling-back
transaction, it attempts to purge the delete-marked record, if possible, in a
separate mini-transaction.

However, row_undo_mod_remove_clust_low() fails to check if the DB_TRX_ID of
the record that it found after repositioning the cursor, is still the same.
If it is not, it means that the record was purged and another record was
inserted in its place.

So, the rollback would have performed an incorrect purge, breaking the
locking rules and causing corruption.

The problem was found by creating a table that contains a unique
secondary index and a primary key, and two threads running REPLACE
with only one value for the unique column, so that the uniqueness
constraint would be violated all the time, leading to statement
rollback.

This bug exists in all InnoDB versions (I checked MySQL 3.23.53).
It has become easier to repeat in 5.5 and 5.6 thanks to scalability
improvements and a dedicated purge thread.

rb#3085 approved by Jimmy Yang

FAILED BLOB WRITE

btr_store_big_rec_extern_fields(): Relax a debug assertion so that
some BLOB pointers may remain zero if an error occurs.

btr_free_externally_stored_field(), row_undo_ins(): Allow the BLOB
pointer to be zero on any rollback.

rb#3059 approved by Jimmy Yang, Kevin Lewis

Problem Description:
A mysqld_safe instance is started. An InnoDB crash recovery begins which takes
few seconds to complete. During this crash recovery process happening, another
mysqld_safe instance is started with the same server startup parameters. Since
the mysqld's pid file is absent during the crash recovery process the second
instance assumes there is no other process and tries to acquire a lock on the
ibdata files in the datadir.  But this step fails and the 2nd instance keeps 
retrying 100 times each with a delay of 1 second. Now after the 100 attempts, 
the server goes down, but while going down it hits the mysqld_safe script's 
cleanup section and without any check it blindly deletes the socket and pid 
files. Since no lock is placed on the socket file, it gets deleted.

Solution:
We create a mysqld_safe.pid file in the datadir, which protects the presence 
server instance resources by storing the mysqld_safe's process id in it. We
place a check if the mysqld_safe.pid file is existing in the datadir. If yes
then we check if the pid it contains is an active pid or not. If yes again,
then the scripts logs an error saying "A mysqld_safe instance is already 
running". Otherwise it will log the present mysqld_safe's pid into the 
mysqld_safe.pid file.