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Commit 8e49f418c9632790bf456634742d34d97120a784

Authored by Vaibhav Nagarnaik
Committed by Steven Rostedt
1 parent 95cf59ea72
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

ring-buffer: Check for uninitialized cpu buffer before resizing 

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-vnagarnaik@google.com

Cc: stable@vger.kernel.org # 3.5+
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Showing 1 changed file with 4 additions and 0 deletions Side-by-side Diff

kernel/trace/ring_buffer.c
Diff comments   View file @ 8e49f41
... ... @@ -1567,6 +1567,10 @@
1567 1567  
1568 1568 put_online_cpus();
1569 1569 } else {
  1570 + /* Make sure this CPU has been intitialized */
  1571 + if (!cpumask_test_cpu(cpu_id, buffer->cpumask))
  1572 + goto out;
  1573 +
1570 1574 cpu_buffer = buffer->buffers[cpu_id];
1571 1575  
1572 1576 if (nr_pages == cpu_buffer->nr_pages)