Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756806Ab2KZRjh (ORCPT ); Mon, 26 Nov 2012 12:39:37 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:47866 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933581Ab2KZRLJ (ORCPT ); Mon, 26 Nov 2012 12:11:09 -0500 From: Herton Ronaldo Krzesinski To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Vaibhav Nagarnaik , Steven Rostedt , Herton Ronaldo Krzesinski Subject: [PATCH 180/270] ring-buffer: Check for uninitialized cpu buffer before resizing Date: Mon, 26 Nov 2012 14:57:50 -0200 Message-Id: <1353949160-26803-181-git-send-email-herton.krzesinski@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> References: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1677 Lines: 48 3.5.7u1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Vaibhav Nagarnaik 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//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 Signed-off-by: Steven Rostedt Signed-off-by: Herton Ronaldo Krzesinski --- kernel/trace/ring_buffer.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index f765465..db6dff1 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) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/