ftrace: Protect direct_functions in ftrace_find_rec_direct

Fix accessing the __rcu pointer direct_functions with RCU protection.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260730150411.88667-2-leon.hwang@linux.dev
Fixes: d05cb470663a ("ftrace: Fix modification of direct_function hash while in use")
Acked-by: Jiri Olsa <jolsa@kernel.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6c47a94f5924784f2726cdaffb240916ae29f62f..c5d1d0d42ccc1d70a4ae5f43667dcdb26ce3d2bc 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2645,7 +2645,8 @@ unsigned long ftrace_find_rec_direct(unsigned long ip)
 {
        struct ftrace_func_entry *entry;
 
-       entry = __ftrace_lookup_ip(direct_functions, ip);
+       guard(preempt_notrace)();
+       entry = __ftrace_lookup_ip(rcu_dereference_sched(direct_functions), ip);
        if (!entry)
                return 0;