CRASHES IN WILD_CASE_COMPARE!
Description:- Executing FLUSH PRIVILEGES and REVOKE/
GRANT concurrently crashes the server.
Analysis:- Concurrent FLUSH PRIVILEGES and REVOKE/GRANT
might trigger a small time frame in which REVOKE/GRANT
fetches the "acl_proxy_user" information as a part of
"acl_check_proxy_grant_access()". Meanwhile FLUSH PRIVILEGES
deletes the old acl structures as a part of "acl_reload()".
After which REVOKE/GRANT tries to access the hostname in
"wild_case_compare()" which leads to a crash because of the
invalid memory access.
Fix:- Mutex lock on "acl_cache" is acquired before fetching
"acl_proxy_user" information in
"acl_check_proxy_grant_access()".
- Part 3: Adding mem_root to push_back() and push_front()
Other things:
- Added THD as an argument to some partition functions.
- Added memory overflow checking for XML tag's in read_xml()
- Added mem_root to all calls to new Item
- Added private method operator new(size_t size) to Item to ensure that
we always use a mem_root when creating an item.
This saves use once call to current_thd per Item creation
Added mandatory thd parameter to Item (and all derivative classes) constructor.
Added thd parameter to all routines that may create items.
Also removed "current_thd" from Item::Item. This reduced number of
pthread_getspecific() calls from 290 to 177 per OLTP RO transaction.
DATABASE WHEN USING TABLE ALIASES
Issue:
-----
When using table aliases for deleting, MySQL checks
privileges against the current database and not the
privileges on the actual table or database the table
resides.
SOLUTION:
---------
While checking privileges for multi-deletes,
correspondent_table should be used since it points to the
correct table and database.
- Changed ER(ER_...) to ER_THD(thd, ER_...) when thd was known or if there was many calls to current_thd in the same function.
- Changed ER(ER_..) to ER_THD_OR_DEFAULT(current_thd, ER...) in some places where current_thd is not necessary defined.
- Removing calls to current_thd when we have access to thd
Part of this is optimization (not calling current_thd when not needed),
but part is bug fixing for error condition when current_thd is not defined
(For example on startup and end of mysqld)
Notable renames done as otherwise a lot of functions would have to be changed:
- In JOIN structure renamed:
examined_rows -> join_examined_rows
record_count -> join_record_count
- In Field, renamed new_field() to make_new_field()
Other things:
- Added DBUG_ASSERT(thd == tmp_thd) in Item_singlerow_subselect() just to be safe.
- Removed old 'tab' prefix in JOIN_TAB::save_explain_data() and use members directly
- Added 'thd' as argument to a few functions to avoid calling current_thd.
Gave priority to password field when using a native authentication
plugin.
Also, prevented a user from setting an invalid auth_string, when using
native authentication.
HOST WHEN IT CONTAINS WILDCARD
Description :- Incorrect access privileges are provided to a
user due to wrong sorting of users when wildcard characters
is present in the hostname.
Analysis :- Function "get_sorts()" is used to sort the
strings of user name, hostname, database name. It is used
to arrange the users in the access privilege matching order.
When a user connects, it checks in the sorted user access
privilege list and finds a corresponding matching entry for
the user. Algorithm used in "get_sort()" sorts the strings
inappropriately. As a result, when a user connects to the
server, it is mapped to incorrect user access privileges.
Algorithm used in "get_sort()" counts the number of
characters before the first occurence of any one of the
wildcard characters (single-wildcard character '_' or
multi-wildcard character '%') and sorts in that order.
As a result of inconnect sorting it treats hostname "%" and
"%.mysql.com" as equally-specific values and therefore
the order is indeterminate.
Fix:- The "get_sort()" algorithm has been modified to treat
"%" seperately. Now "get_sort()" returns a number which, if
sorted in descending order, puts strings in the following
order:-
* strings with no wildcards
* strings containg wildcards and non-wildcard characters
* single muilt-wildcard character('%')
* empty string.
- Fixed compiler warnings
- Added include/wait_for_binlog_checkpoint.inc, as suggested by JonasO
- Updated 'build-tags' to work with git (Patch by Serg)
* reset current_thd in THD::~THD, otherwise my_malloc_size_cb_func()
might access THD after it was destroyed.
* remove now redundant set_current_thd(0) calls that follow delete thd.
* indeed, "username IDENTIFIED BY PASSWORD hash" is the same
as "username IDENTIFIED VIA mysql_native_password USING hash"
* LEX_USER::password can now be used for plain-text passwords
