Protect all READ_ONLY sysvars from run-time changes.
Put them into a separate section and use my_virtual_mem_protect()
to make this section read-only before the server starts accepting
connections.
Verify that they're all protected in the sys_var constructor.
One exception: opt_noacl (--skip-grant-tables) can be changed
from 1 to 0 on FLUSH PRIVILEGES. Let's briefly drop the
protection for this 1->0 change. It can be needed only once
in a server lifetime and only if it was started with --skip-grant-tables
On shutdown the protection is removed, making variables writable
again because shutdown resets some of them during the cleanup
Assisted-By: Claude:claude-4.8-opus
The json_engine killed_ptr was of type uchar however the enum
in the server is dependant on the architecture. On big-endian
architectures like IBM Z, retreiving a uchar* retreived the
unmodifed part of the THD->kill enum location and was always 0.
As C++11 allows enums to inherit a type, used uint32_t as the base
class of killed_state type in the server and used uint32_t in the
json library.
reload_acl_and_cache required an expression change to avoid
the compile error:
sql/sql_reload.cc:472:24: error: enumerated and non-enumerated
type in conditional expression [-Werror=enum-conversion]
472 | return result || (thd ? thd->killed : 0);
Added the kill_ptr assignment the following functions can be
killed:
* Item_func_json_depth::val_int
* Item_func_json_type::val_str
* Item_func_json_length::val_int
Item_func_json_array_append::val_str, check_killed() only applied
to json_error: label and not return_null.
Item_func_json_overlaps::val_bool ensure check_killed() is called.
Item_func_json_format::val_str(), corresponding to the SQL,
json_compact, json_detailed, json_loose - add debug instrumentation
for the func_json_notembedded test.
MDEV-26726 (fcd345de48) added a json_pause_execution sync point
however the test case used debug_max_statement_time, which doesn't
exist. Fix the sync point name in the test.
The problem was that when using clang + asan, we do not get a correct value
for the thread stack as some local variables are not allocated at the
normal stack.
It looks like that for example clang 18.1.3, when compiling with
-O2 -fsanitize=addressan it puts local variables and things allocated by
alloca() in other areas than on the stack.
The following code shows the issue
Thread 6 "mariadbd" hit Breakpoint 3, do_handle_one_connection
(connect=0x5080000027b8,
put_in_cache=<optimized out>) at sql/sql_connect.cc:1399
THD *thd;
1399 thd->thread_stack= (char*) &thd;
(gdb) p &thd
(THD **) 0x7fffedee7060
(gdb) p $sp
(void *) 0x7fffef4e7bc0
The address of thd is 24M away from the stack pointer
(gdb) info reg
...
rsp 0x7fffef4e7bc0 0x7fffef4e7bc0
...
r13 0x7fffedee7060 140737185214560
r13 is pointing to the address of the thd. Probably some kind of
"local stack" used by the sanitizer
I have verified this with gdb on a recursive call that calls alloca()
in a loop. In this case all objects was stored in a local heap,
not on the stack.
To solve this issue in a portable way, I have added two functions:
my_get_stack_pointer() returns the address of the current stack pointer.
The code is using asm instructions for intel 32/64 bit, powerpc,
arm 32/64 bit and sparc 32/64 bit.
Supported compilers are gcc, clang and MSVC.
For MSVC 64 bit we are using _AddressOfReturnAddress()
As a fallback for other compilers/arch we use the address of a local
variable.
my_get_stack_bounds() that will return the address of the base stack
and stack size using pthread_attr_getstack() or NtCurrentTed() with
fallback to using the address of a local variable and user provided
stack size.
Server changes are:
- Moving setting of thread_stack to THD::store_globals() using
my_get_stack_bounds().
- Removing setting of thd->thread_stack, except in functions that
allocates a lot on the stack before calling store_globals(). When
using estimates for stack start, we reduce stack_size with
MY_STACK_SAFE_MARGIN (8192) to take into account the stack used
before calling store_globals().
I also added a unittest, stack_allocation-t, to verify the new code.
Reviewed-by: Sergei Golubchik <serg@mariadb.org>
Improve detection for DES support in OpenSSL, to allow compilation
against system OpenSSL without DES.
Note that MariaDB needs to be compiled against OpenSSL-like library
that itself has DES support which cmake detected. Positive detection
is indicated with CMake variable HAVE_des 1.
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@surgut.co.uk>
The signal handler thread can use various different runtime
resources when processing a SIGHUP (e.g. master-info information)
due to calling into reload_acl_and_cache(). Currently, the shutdown
process waits for the termination of the signal thread after
performing cleanup. However, this could cause resources actively
used by the signal handler to be freed while reload_acl_and_cache()
is processing.
The specific resource that caused MDEV-30260 is a race condition for
the hostname_cache, such that mysqld would delete it in
clean_up()::hostname_cache_free(), before the signal handler would
use it in reload_acl_and_cache()::hostname_cache_refresh().
Another similar resource is the active_mi/master_info_index. There
was a race between its deletion by the main thread in end_slave(),
and their usage by the Signal Handler as a part of
Master_info_index::flush_all_relay_logs.read(active_mi) in
reload_acl_and_cache().
This patch fixes these race conditions by relocating where server
shutdown waits for the signal handler to die until after
server-level threads have been killed (i.e., as a last step of
close_connections()). With respect to the hostname_cache, active_mi
and master_info_cache, this ensures that they cannot be destroyed
while the signal handler is still active, and potentially using
them.
Additionally:
1) This requires that Events memory is still in place for SIGHUP
handling's mysql_print_status(). So event deinitialization is moved
into clean_up(), but the event scheduler still needs to be stopped
in close_connections() at the same spot.
2) The function kill_server_thread is no longer used, so it is
deleted
3) The timeout to wait for the death of the signal thread was not
consistent with the comment. The comment mentioned up to 10 seconds,
whereas it was actually 0.01s. The code has been fixed to wait up to
10 seconds.
4) A warning has been added if the signal handler thread fails to
exit in time.
5) Added pthread_join() to end of wait_for_signal_thread_to_end()
if it hadn't ended in 10s with a warning. Note this also removes
the pthread_detached attribute from the signal_thread to allow
for the pthread_join().
Reviewed By:
===========
Vladislav Vaintroub <wlad@mariadb.com>
Andrei Elkin <andrei.elkin@mariadb.com>
Making changes to wsrep_mysqld.h causes large parts of server code to
be recompiled. The reason is that wsrep_mysqld.h is included by
sql_class.h, even tough very little of wsrep_mysqld.h is needed in
sql_class.h. This commit introduces a new header file, wsrep_on.h,
which is meant to be included from sql_class.h, and contains only
macros and variable declarations used to determine whether wsrep is
enabled.
Also, header wsrep.h should only contain definitions that are also
used outside of sql/. Therefore, move WSREP_TO_ISOLATION* and
WSREP_SYNC_WAIT macros to wsrep_mysqld.h.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
Trigger `socket.ssl_reload` when FLUSH SSL is issued. To triger reloading
of certificate, key and CA, files needs to be physically changed.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
MDEV-20945: BACKUP UNLOCK + FTWRL assertion failure | SIGSEGV in I_P_List
from MDL_context::release_lock on INSERT w/ BACKUP LOCK (on optimized
builds) | Assertion `ticket->m_duration == MDL_EXPLICIT' failed
BACKUP LOCK behavior is modified so it won't be used wrong:
- BACKUP LOCK should commit any active transactions.
- BACKUP LOCK should not be allowed in stored procedures.
- When BACKUP LOCK is active, don't allow any DDL's for that connection.
- FTWRL is forbidden on the same connection while BACKUP LOCK is active.
Reviewed-by: monty@mariadb.com
Rather than flushing caches with tdc_remove_table(TDC_RT_REMOVE_UNUSED)
flush them with extra(HA_EXTRA_FLUSH) instead. This goes inline with
regular FTWRL.
Part of MDEV-17882 - Cleanup refresh version
Reverted original patch (c2e0a0b).
For consistency with "LOCK TABLE <table_name> READ" and "FLUSH TABLES
WITH READ LOCK", which are forbidden under "BACKUP STAGE", forbid "FLUSH
TABLE <table_name> FOR EXPORT" and "FLUSH TABLE <table_name> WITH READ
LOCK" as well.
It'd allow consistent fixes for problems like MDEV-18643.
After 7fb9d64 it is used only by ALTER/DROP SERVER, which most probably
wasn't intentional as Federated never supported delayed inserts anyway.
If delayed inserts will ever become an issue with ALTER/DROP SERVER, we
should kill them by acquiring X-lock instead.
Part of MDEV-17882 - Cleanup refresh version
