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tracing: Return error if ftrace_trace_arrays list is empty

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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>
This commit is contained in:
Yoshihiro YUNOMAE
2014-06-06 07:35:17 +09:00
committed by Steven Rostedt
parent 34839f5a69
commit dc81e5e3ab
2 changed files with 16 additions and 0 deletions
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3
kernel/trace/trace.h
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@@ -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));