bpf: Cleanup ftrace hash in bpf_trampoline_put

We need to release possible hash from trampoline fops object
before removing it, otherwise we leak it.

Fixes: 00963a2e ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20220802135651.1794015-1-jolsa@kernel.org

kernel/bpf/trampoline.c

@@ -841,7 +841,10 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
 	 * multiple rcu callbacks.
 	 */
 	hlist_del(&tr->hlist);
-	kfree(tr->fops);
+	if (tr->fops) {
+		ftrace_free_filter(tr->fops);
+		kfree(tr->fops);
+	}
 	kfree(tr);
 out:
 	mutex_unlock(&trampoline_mutex);