Re: [PATCH ftrace/core 1/3] trace/event: Return error if ftrace_trace_arrays is empty list

[Steven Rostedt]

On Fri, 06 Jun 2014 07:35:17 +0900
Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@xxxxxxxxxxx> wrote:

> 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.

As I'm still working on some more patches for 3.16, I can add this.
It's not that critical, because if global_array fails to allocate on
boot up, lots of other things may also break.

-- Steve

> 
> Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@xxxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
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