[for-linus][PATCH 2/2] tracing: Fix pid filtering when triggers are attached

Steven Rostedt
2021-11-27T18:23:11Z

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

If a event is filtered by pid and a trigger that requires processing of
the event to happen is a attached to the event, the discard portion does
not take the pid filtering into account, and the event will then be
recorded when it should not have been.

Cc: stable@vger.kernel.org
Fixes: 3fdaf80f4a836 ("tracing: Implement event pid filtering")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace.h | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6b60ab9475ed..38715aa6cfdf 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1366,14 +1366,26 @@ __event_trigger_test_discard(struct trace_event_file *file,
if (eflags & EVENT_FILE_FL_TRIGGER_COND)
*tt = event_triggers_call(file, buffer, entry, event);

- if (test_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags) ||
- (unlikely(file->flags & EVENT_FILE_FL_FILTERED) &&
- !filter_match_preds(file->filter, entry))) {
- __trace_event_discard_commit(buffer, event);
- return true;
- }
+ if (likely(!(file->flags & (EVENT_FILE_FL_SOFT_DISABLED |
+ EVENT_FILE_FL_FILTERED |
+ EVENT_FILE_FL_PID_FILTER))))
+ return false;
+
+ if (file->flags & EVENT_FILE_FL_SOFT_DISABLED)
+ goto discard;
+
+ if (file->flags & EVENT_FILE_FL_FILTERED &&
+ !filter_match_preds(file->filter, entry))
+ goto discard;
+
+ if ((file->flags & EVENT_FILE_FL_PID_FILTER) &&
+ trace_event_ignore_this_pid(file))
+ goto discard;

return false;
+ discard:
+ __trace_event_discard_commit(buffer, event);
+ return true;
}

/**
--
2.33.0