tracing: Fix memory leak of instance function hash filters

BugLink: https://bugs.launchpad.net/bugs/1837257
commit 2840f84f74035e5a535959d5f17269c69fa6edc5 upstream.

The following commands will cause a memory leak:

 # cd /sys/kernel/tracing
 # mkdir instances/foo
 # echo schedule > instance/foo/set_ftrace_filter
 # rmdir instances/foo

The reason is that the hashes that hold the filters to set_ftrace_filter and
set_ftrace_notrace are not freed if they contain any data on the instance
and the instance is removed.

Found by kmemleak detector.

Cc: stable@vger.kernel.org
Fixes: 591dffdade9f ("ftrace: Allow for function tracing instance to filter functions")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 271e4ced97ad1ba6f1669814c01689c2b97a4f31..b11a778c0b05dddfca99a03a989dfffbdffc07f5 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5502,6 +5502,7 @@ void ftrace_destroy_filter_files(struct ftrace_ops *ops)
        if (ops->flags & FTRACE_OPS_FL_ENABLED)
                ftrace_shutdown(ops, 0);
        ops->flags |= FTRACE_OPS_FL_DELETED;
+       ftrace_free_filter(ops);
        mutex_unlock(&ftrace_lock);
 }