diff options
| author | Vaibhav Nagarnaik <vnagarnaik@google.com> | 2012-10-10 16:40:27 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-28 10:56:10 -0700 |
| commit | c46d0da8fad7ef10a6f86ebd698fba26e7cadcf5 (patch) | |
| tree | 508036fcbf23a2425f968a74d48b0c9cb36c4333 /kernel | |
| parent | 3e75581ec02473059597582fa24cf077f0e20b1b (diff) | |
ring-buffer: Check for uninitialized cpu buffer before resizing
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-vnagarnaik@google.com
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 49491fa7daa2..ebd284f63e1b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1567,6 +1567,10 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, 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) |