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.