From: Steven Rostedt <rostedt@goodmis.org>
Triggers are now delayed from freeing, but can still be triggered until
after the RCU grace period has ended. The freeing of the enable_event data
is put into the private_data_free() callback, but the put of the module
refcount is done immediately.
It is possible that if a module is removed that has an event that would
enable (or disable) it is still active, it can read the data of the module
after it is removed causing a use-after-free bug.
Move the trace_event_put_ref() that releases the module into the delayed
callback so that the module can not be removed until any reference to its
events are finished.
Cc: stable@vger.kernel.org
Reported-by: sashiko-bot@kernel.org
Link: https://sashiko.dev/#/patchset/20260724030523.19081-1-devnexen%40gmail.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_events_trigger.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 46e60b70a4bb..ad83419cb420 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -1726,7 +1726,10 @@ int event_enable_trigger_print(struct seq_file *m,
static void enable_trigger_private_data_free(struct event_trigger_data *data)
{
- kfree(data->private_data);
+ struct enable_trigger_data *enable_data = data->private_data;
+
+ trace_event_put_ref(enable_data->file->event_call);
+ kfree(enable_data);
}
void event_enable_trigger_free(struct event_trigger_data *data)
@@ -1741,7 +1744,6 @@ void event_enable_trigger_free(struct event_trigger_data *data)
/* Remove the SOFT_MODE flag */
trace_event_enable_disable(enable_data->file, 0, 1);
data->private_data_free = enable_trigger_private_data_free;
- trace_event_put_ref(enable_data->file->event_call);
trigger_data_free(data);
}
}
--
2.53.0