From: tip-bot for Vaibhav Nagarnaik <vnagarnaik@google.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, vnagarnaik@google.com,
hpa@zytor.com, mingo@kernel.org, rostedt@goodmis.org,
tglx@linutronix.de
Subject: [tip:perf/urgent] ring-buffer: Check for uninitialized cpu buffer before resizing
Date: Sun, 21 Oct 2012 11:37:24 -0700 [thread overview]
Message-ID: <tip-8e49f418c9632790bf456634742d34d97120a784@git.kernel.org> (raw)
In-Reply-To: <1349912427-6486-1-git-send-email-vnagarnaik@google.com>
Commit-ID: 8e49f418c9632790bf456634742d34d97120a784
Gitweb: http://git.kernel.org/tip/8e49f418c9632790bf456634742d34d97120a784
Author: Vaibhav Nagarnaik <vnagarnaik@google.com>
AuthorDate: Wed, 10 Oct 2012 16:40:27 -0700
Committer: Steven Rostedt <rostedt@goodmis.org>
CommitDate: Thu, 11 Oct 2012 12:21:48 -0400
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 | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b32ed0e..b979426 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)
prev parent reply other threads:[~2012-10-21 18:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 23:40 [PATCH] ring-buffer: Check for uninitialized cpu buffer before resizing Vaibhav Nagarnaik
2012-10-21 18:37 ` tip-bot for Vaibhav Nagarnaik [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=tip-8e49f418c9632790bf456634742d34d97120a784@git.kernel.org \
--to=vnagarnaik@google.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).