tracing: Return error if ftrace_trace_arrays list is empty (dc81e5e3) · Commits · 戴 / test

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:

Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

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");

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