3.6-stable review patch. If anyone has any objections, please let me know.
------------------ From: Vaibhav Nagarnaik <vnagarn...@google.com> commit 8e49f418c9632790bf456634742d34d97120a784 upstream. With a system where, num_present_cpus < num_possible_cpus, even if all CPUs are online, non-present CPUs don't have per_cpu buffers allocated. If per_cpu/<cpu>/buffer_size_kb is modified for such a CPU, it can cause a panic due to NULL dereference in ring_buffer_resize(). To fix this, resize operation is allowed only if the per-cpu buffer has been initialized. Link: http://lkml.kernel.org/r/1349912427-6486-1-git-send-email-vnagarn...@google.com Signed-off-by: Vaibhav Nagarnaik <vnagarn...@google.com> Signed-off-by: Steven Rostedt <rost...@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- kernel/trace/ring_buffer.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1567,6 +1567,10 @@ int ring_buffer_resize(struct ring_buffe put_online_cpus(); } else { + /* Make sure this CPU has been intitialized */ + if (!cpumask_test_cpu(cpu_id, buffer->cpumask)) + goto out; + cpu_buffer = buffer->buffers[cpu_id]; if (nr_pages == cpu_buffer->nr_pages) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
