lkml.org 
[lkml]   [2014]   [Jun]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH ftrace/core 1/2] [BUGFIX] ftrace: Avoid panic when allocation of max_buffer is failed
On Tue, 03 Jun 2014 13:28:03 +0900
Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> wrote:

> When allocation of max_buffer is failed, the kernel frees tr->trace_buffer.data
> per CPU and return -ENOMEM in allocate_trace_buffers(). However,
> tracer_alloc_buffers() calling allocate_trace_buffers() also frees the data
> per CPU for -ENOMEM by allocate_trace_buffers(). Therefore, the allocation
> failure induces double free.
>
> For the out_free_mask path in tracer_alloc_buffers(),
> global_trace.trace_buffer.data and global_trace.max_buffer.data are
> not allocated yet, so free_percpu of those are not needed.
>
> Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: linux-kernel@vger.kernel.org
> ---
> kernel/trace/trace.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 626dbfd..135af32 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -6671,10 +6671,6 @@ __init static int tracer_alloc_buffers(void)
> out_free_temp_buffer:
> ring_buffer_free(temp_buffer);
> out_free_cpumask:
> - free_percpu(global_trace.trace_buffer.data);
> -#ifdef CONFIG_TRACER_MAX_TRACE
> - free_percpu(global_trace.max_buffer.data);
> -#endif
> free_cpumask_var(global_trace.tracing_cpumask);
> out_free_buffer_mask:
> free_cpumask_var(tracing_buffer_mask);

OK, so this is a double free on an error path at boot up. As it is
highly unlikely, I'll just add it for my 3.16 queue. It doesn't need to
go to stable.

-- Steve


\
 
 \ /
  Last update: 2014-06-04 02:41    [W:0.180 / U:0.372 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site