From: Steven Rostedt rostedt@goodmis.org

On some paths in print_event_fields() it takes the trace_event_sem for read, even though it should always be held when the function is called.

Remove the taking of that mutex and add a lockdep_assert_held_read() to make sure the trace_event_sem is held when print_event_fields() is called.

Cc: stable@vger.kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/20250501224128.0b1f0571@batman.local.home Fixes: 80a76994b2d88 ("tracing: Add "fields" option to show raw trace event fields") Reported-by: syzbot+441582c1592938fccf09@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6813ff5e.050a0220.14dd7d.001b.GAE@google.com/ Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- kernel/trace/trace_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index fee40ffbd490..b9ab06c99543 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1042,11 +1042,12 @@ enum print_line_t print_event_fields(struct trace_iterator *iter, struct trace_event_call *call; struct list_head *head;

+ lockdep_assert_held_read(&trace_event_sem); + /* ftrace defined events have separate call structures */ if (event->type <= __TRACE_LAST_TYPE) { bool found = false;

- down_read(&trace_event_sem); list_for_each_entry(call, &ftrace_events, list) { if (call->event.type == event->type) { found = true; @@ -1056,7 +1057,6 @@ enum print_line_t print_event_fields(struct trace_iterator *iter, if (call->event.type > __TRACE_LAST_TYPE) break; } - up_read(&trace_event_sem); if (!found) { trace_seq_printf(&iter->seq, "UNKNOWN TYPE %d\n", event->type); goto out;