In the Linux kernel, the following vulnerability has been resolved:

tracing: Delay module ref count for "enable_event" trigger

Triggers are now delayed from freeing, but can still be triggered until
after the RCU grace period has ended. The freeing of the enable_event data
is put into the private_data_free() callback, but the put of the module
refcount is done immediately.

It is possible that if a module is removed that has an event that would
enable (or disable) it is still active, it can read the data of the module
after it is removed causing a use-after-free bug.

Move the trace_event_put_ref() that releases the module into the delayed
callback so that the module can not be removed until any reference to its
events are finished.