ring-buffer: Check for uninitialized cpu buffer before resizing
authorVaibhav Nagarnaik <vnagarnaik@google.com>
Wed, 10 Oct 2012 23:40:27 +0000 (16:40 -0700)
committerSteven Rostedt <rostedt@goodmis.org>
Thu, 11 Oct 2012 16:21:48 +0000 (12:21 -0400)
commit8e49f418c9632790bf456634742d34d97120a784
treedfe1caca880206a3cfb38c923e49a5af74071d87
parent95cf59ea72331d0093010543b8951bb43f262cac
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>
kernel/trace/ring_buffer.c