CVE-2026-97443

About vulnerability

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.

Affected product:

Debian 10 ELS , Debian 11 ELS , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

linux @ 5.4.0 (+4 more)

Live-patch status from KernelCare for each operating system.