CVE-2026-97443

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

perf/ftrace: Fix WARNING in __unregister_ftrace_function

perf_ftrace_function_unregister() unconditionally calls

unregister_ftrace_function() without checking whether the ftrace_ops

was ever successfully registered. This triggers a WARN_ON in

__unregister_ftrace_function() when the ops doesn't have

FTRACE_OPS_FL_ENABLED set.

This can happen during perf_event_alloc() error cleanup when

perf_trace_destroy() is called via __free_event() on an event whose

ftrace_ops registration failed or was already torn down by

perf_try_init_event()'s err_destroy path.

The call path is:

perf_event_alloc() error cleanup

-> __free_event()

-> event->destroy() [tp_perf_event_destroy]

-> perf_trace_destroy()

-> perf_trace_event_close()

-> TRACE_REG_PERF_CLOSE

-> perf_ftrace_function_unregister()

-> unregister_ftrace_function()

-> __unregister_ftrace_function()

-> WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED))

Fix this by checking FTRACE_OPS_FL_ENABLED before attempting to

unregister. If the ops is not enabled, just free the filter and

return success.