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[209.132.180.67]) by mx.google.com with ESMTP id b16si1655701edb.341.2019.10.17.07.16.53; Thu, 17 Oct 2019 07:17:16 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b="0PcJ/0cX"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437636AbfJPVyB (ORCPT + 99 others); Wed, 16 Oct 2019 17:54:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:43282 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437591AbfJPVxy (ORCPT ); Wed, 16 Oct 2019 17:53:54 -0400 Received: from localhost (unknown [192.55.54.58]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 047A0218DE; Wed, 16 Oct 2019 21:53:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571262834; bh=XzCMom3IC3SYUResNnRRzR+p0658IoGw/WlSDIjtbrk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0PcJ/0cXyoBYt/fznVeFZNdqAlhBmyge0+wIDWmMSO5BZ0mv5ooaoYlO6GjXWz2Lv rQ5KCgO6ikCl2NUvvIw4ZzPZR477xGsNdhv/GG+Tx5jhSIDhlVu7tAuvEcZfMvjr46 ta0cisCyeeKR/Obg0ahfNR825eZ/ggx06CzRmIh0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Steven Rostedt (VMware)" Subject: [PATCH 4.4 77/79] tracing: Get trace_array reference for available_tracers files Date: Wed, 16 Oct 2019 14:50:52 -0700 Message-Id: <20191016214834.008090257@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191016214729.758892904@linuxfoundation.org> References: <20191016214729.758892904@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt (VMware) commit 194c2c74f5532e62c218adeb8e2b683119503907 upstream. As instances may have different tracers available, we need to look at the trace_array descriptor that shows the list of the available tracers for the instance. But there's a race between opening the file and an admin deleting the instance. The trace_array_get() needs to be called before accessing the trace_array. Cc: stable@vger.kernel.org Fixes: 607e2ea167e56 ("tracing: Set up infrastructure to allow tracers for instances") Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3370,9 +3370,14 @@ static int show_traces_open(struct inode if (tracing_disabled) return -ENODEV; + if (trace_array_get(tr) < 0) + return -ENODEV; + ret = seq_open(file, &show_traces_seq_ops); - if (ret) + if (ret) { + trace_array_put(tr); return ret; + } m = file->private_data; m->private = tr; @@ -3380,6 +3385,14 @@ static int show_traces_open(struct inode return 0; } +static int show_traces_release(struct inode *inode, struct file *file) +{ + struct trace_array *tr = inode->i_private; + + trace_array_put(tr); + return seq_release(inode, file); +} + static ssize_t tracing_write_stub(struct file *filp, const char __user *ubuf, size_t count, loff_t *ppos) @@ -3410,8 +3423,8 @@ static const struct file_operations trac static const struct file_operations show_traces_fops = { .open = show_traces_open, .read = seq_read, - .release = seq_release, .llseek = seq_lseek, + .release = show_traces_release, }; static ssize_t