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 empty list. If ftrace_trace_arrays is empty list,
current top_trace_array() returns 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.
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae...@hitachi.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: linux-kernel@vger.kernel.org
---
kernel/trace/trace.h | 3 +++
kernel/trace/trace_events.c | 13 +++++++++++++
2 files changed, 16 insertions(+)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 217207a..9e82551 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -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));
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 3ddfd8f..1349870 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -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 -ENODEV;
pr_info("Running tests on trace events:\n");
--
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