From 40e26815fafd3b8c4aced17b1f22e68ef33eb8db Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 10 Mar 2009 11:32:40 -0400 Subject: [PATCH] tracing: do not allow modifying the ftrace events via the event files Impact: fix to prevent crash on calling NULL function pointer The ftrace internal records have their format exported via the event system under the ftrace subsystem. These are only for exporting the format to allow binary readers to be able to parse them in a binary output. The ftrace subsystem events can only be enabled via the ftrace tracers and do not have a registering function. The event files expect the event record to have registering function and will call it directly. Passing in a ftrace subsystem event will cause the kernel to crash because it will execute a NULL pointer. This patch prevents the ftrace subsystem from being viewable to the event enabling files. Signed-off-by: Steven Rostedt --- kernel/trace/trace_events.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index a0b41cc26f26..85ec10fbb38d 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -102,7 +102,7 @@ static int ftrace_set_clr_event(char *buf, int set) mutex_lock(&event_mutex); events_for_each(call) { - if (!call->name) + if (!call->name || !call->regfunc) continue; if (match && @@ -207,8 +207,20 @@ t_next(struct seq_file *m, void *v, loff_t *pos) (*pos)++; - if ((unsigned long)call >= (unsigned long)__stop_ftrace_events) - return NULL; + for (;;) { + if ((unsigned long)call >= (unsigned long)__stop_ftrace_events) + return NULL; + + /* + * The ftrace subsystem is for showing formats only. + * They can not be enabled or disabled via the event files. + */ + if (call->regfunc) + break; + + call++; + next = call; + } m->private = ++next; -- 2.20.1