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MDEV-36893 THD::reset_sub_statement_state swaps with uninitialized structure

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THD::reset_sub_statement_state and THD::restore_sub_staement_state
swap auto_inc_intervals_forced(Discrete_intervals_list) of a THD class
with a local variable temporary to execute other things before restoring
at the end of Table_triggers_list::process_triggers under a
rpl_master_erroneous_autoinc(true) condition as exposed by the
rpl.rpl_trigger test.

The uninitialized data isn't used and the only required action is to
copy the data in one direction. As the intent is for the auto_inc_intervals_forced
value to be overwritten or unused, MEM_UNDEFINED is used on it to
ensure the previous state is considered invalid.

The other uses of reset_sub_statement_state in Item_sp::execute_impl
also follow the same pattern of taking a copy to restore within the
same function.
This commit is contained in:
Daniel Black
2025-05-28 11:48:04 +10:00
parent 8d2665e56b
commit 495153feac
1 changed files with 3 additions and 2 deletions
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5
sql/sql_class.cc
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@@ -5913,7 +5913,8 @@ void THD::reset_sub_statement_state(Sub_statement_state *backup,
if (rpl_master_erroneous_autoinc(this))
{
DBUG_ASSERT(backup->auto_inc_intervals_forced.nb_elements() == 0);
auto_inc_intervals_forced.swap(&backup->auto_inc_intervals_forced);
backup->auto_inc_intervals_forced.copy_shallow(&auto_inc_intervals_forced);
MEM_UNDEFINED(&auto_inc_intervals_forced, sizeof auto_inc_intervals_forced);
}
#endif
@@ -5961,7 +5962,7 @@ void THD::restore_sub_statement_state(Sub_statement_state *backup)
*/
if (rpl_master_erroneous_autoinc(this))
{
backup->auto_inc_intervals_forced.swap(&auto_inc_intervals_forced);
auto_inc_intervals_forced.copy_shallow(&backup->auto_inc_intervals_forced);
DBUG_ASSERT(backup->auto_inc_intervals_forced.nb_elements() == 0);
}
#endif