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Commit dc81e5e3 authored by Yoshihiro YUNOMAE's avatar Yoshihiro YUNOMAE Committed by Steven Rostedt
Browse files

tracing: Return error if ftrace_trace_arrays list is empty 

ftrace_trace_arrays links global_trace.list. However, global_trace
is not added to ftrace_trace_arrays if trace_alloc_buffers() failed.
As the result, ftrace_trace_arrays becomes an empty list. If
ftrace_trace_arrays is an empty list, current top_trace_array() returns
an invalid pointer. As the result, the kernel can induce memory corruption
or panic.

Current implementation does not check whether ftrace_trace_arrays is empty
list or not. So, in this patch, if ftrace_trace_arrays is empty list,
top_trace_array() returns NULL. Moreover, this patch makes all functions
calling top_trace_array() handle it appropriately.

Link: http://lkml.kernel.org/p/20140605223517.32311.99233.stgit@yunodevel



Signed-off-by: default avatarYoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 34839f5a

kernel/trace/trace.h

+3 −0
Original line number Diff line number Diff line
@@ -252,6 +252,9 @@ static inline struct trace_array *top_trace_array(void) 
{

	struct trace_array *tr;



	if (list_empty(ftrace_trace_arrays.prev))

		return NULL;



	tr = list_entry(ftrace_trace_arrays.prev,

			typeof(*tr), list);

	WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));

kernel/trace/trace_events.c

+13 −0
Original line number Diff line number Diff line
@@ -574,6 +574,9 @@ int trace_set_clr_event(const char *system, const char *event, int set) 
{

	struct trace_array *tr = top_trace_array();



	if (!tr)

		return -ENODEV;



	return __ftrace_set_clr_event(tr, NULL, system, event, set);

}

EXPORT_SYMBOL_GPL(trace_set_clr_event);
@@ -2065,6 +2068,9 @@ event_enable_func(struct ftrace_hash *hash, 
	bool enable;

	int ret;



	if (!tr)

		return -ENODEV;



	/* hash funcs only work with set_ftrace_filter */

	if (!enabled || !param)

		return -EINVAL;
@@ -2396,6 +2402,9 @@ static __init int event_trace_enable(void) 
	char *token;

	int ret;



	if (!tr)

		return -ENODEV;



	for_each_event(iter, __start_ftrace_events, __stop_ftrace_events) {



		call = *iter;
@@ -2442,6 +2451,8 @@ static __init int event_trace_init(void) 
	int ret;



	tr = top_trace_array();

	if (!tr)

		return -ENODEV;



	d_tracer = tracing_init_dentry();

	if (!d_tracer)
@@ -2535,6 +2546,8 @@ static __init void event_trace_self_tests(void) 
	int ret;



	tr = top_trace_array();

	if (!tr)

		return;



	pr_info("Running tests on trace events:\n");