Commit-ID: 40e26815fafd3b8c4aced17b1f22e68ef33eb8db
Gitweb: http://git.kernel.org/tip/40e26815fafd3b8c4aced17b1f22e68ef33eb8db
Author: "Steven Rostedt" <srostedt@xxxxxxxxxx>
AuthorDate: Tue, 10 Mar 2009 11:32:40 -0400
Commit: Steven Rostedt <srostedt@xxxxxxxxxx>
CommitDate: Tue, 10 Mar 2009 11:32:40 -0400
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 <srostedt@xxxxxxxxxx>
---
kernel/trace/trace_events.c | 18 +++++++++++++++---
1 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index a0b41cc..85ec10f 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;
--
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