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
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 c5e8299d1842..aa0d3663f754 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1056,11 +1056,12 @@ 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;
@@ -1070,7 +1071,6 @@ 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;
--
2.47.2