From: Leon Hwang <leon.hwang@linux.dev>
To: Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Jiri Olsa <jolsa@kernel.org>, Andrii Nakryiko <andrii@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
Leon Hwang <leon.hwang@linux.dev>,
stable@vger.kernel.org
Subject: [PATCH 1/4] ftrace: Protect direct_functions in ftrace_find_rec_direct
Date: Thu, 30 Jul 2026 23:04:08 +0800 [thread overview]
Message-ID: <20260730150411.88667-2-leon.hwang@linux.dev> (raw)
In-Reply-To: <20260730150411.88667-1-leon.hwang@linux.dev>
Fix accessing the __rcu pointer direct_functions with RCU protection.
Cc: stable@vger.kernel.org
Fixes: d05cb470663a ("ftrace: Fix modification of direct_function hash while in use")
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
kernel/trace/ftrace.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6c47a94f5924..c5d1d0d42ccc 100644
--- 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;
--
2.55.0
next prev parent reply other threads:[~2026-07-30 15:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-30 15:04 [PATCH 0/4] ftrace: Protect RCU accesses to direct_functions Leon Hwang
2026-07-30 15:04 ` Leon Hwang [this message]
2026-07-30 15:04 ` [PATCH 2/4] ftrace: Protect direct_functions in update_ftrace_direct_del Leon Hwang
2026-07-30 15:04 ` [PATCH 3/4] ftrace: Protect direct_functions in update_ftrace_direct_mod Leon Hwang
2026-07-30 15:04 ` [PATCH 4/4] ftrace: Drop extra comma in trace_buffered_event_enable Leon Hwang
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