tracing: Change event_filter_read/write to verify i_private != NULL
authorOleg Nesterov <oleg@redhat.com>
Fri, 26 Jul 2013 17:25:40 +0000 (19:25 +0200)
committerSteven Rostedt <rostedt@goodmis.org>
Tue, 30 Jul 2013 02:56:59 +0000 (22:56 -0400)
commite2912b091c26b8ea95e5e00a43a7ac620f6c94a6
tree841eb09f7732ba1d1eb58405743bb61c8a88b2fe
parentbc6f6b08dee5645770efb4b76186ded313f23752
tracing: Change event_filter_read/write to verify i_private != NULL

event_filter_read/write() are racy, ftrace_event_call can be already
freed by trace_remove_event_call() callers.

1. Shift mutex_lock(event_mutex) from print/apply_event_filter to
   the callers.

2. Change the callers, event_filter_read() and event_filter_write()
   to read i_private under this mutex and abort if it is NULL.

This fixes nothing, but now we can change debugfs_remove("filter")
callers to nullify ->i_private and fix the the problem.

Link: http://lkml.kernel.org/r/20130726172540.GA3619@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
kernel/trace/trace_events.c
kernel/trace/trace_events_filter.c