From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC042FA3728 for ; Wed, 16 Oct 2019 21:55:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96F17222C1 for ; Wed, 16 Oct 2019 21:55:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571262938; bh=wrJC8ofyYVGM3ZMkVOPjmMsV1QlKH9zkBK4eiceb2GA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=a3dNlRozqe/2kEU/9RFaH+bY9O52sHOv7jHf6RkAr2SwXFXTo6TzGuiVXXIxC7TcR FWUeV1CmunKXNfW+8XCA4VetVabq0YH1y50zhAWboq2wogNuHuEtxU4YB8S2zXSkZ0 p5tg9C/C/kOiyJBUfGEtvVkHsEbm7bQZx9cSRCiQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395271AbfJPVzg (ORCPT ); Wed, 16 Oct 2019 17:55:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:46280 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395238AbfJPVzb (ORCPT ); Wed, 16 Oct 2019 17:55:31 -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 9F91D21A4C; Wed, 16 Oct 2019 21:55:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571262930; bh=wrJC8ofyYVGM3ZMkVOPjmMsV1QlKH9zkBK4eiceb2GA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l1CkTOlmJ+oRtpx5p+UTgj+yw0nSGtXdnWkYe4syM+MB26QXJD78Bg/20ZsXabqKt Ec7mwnJ2iJs27W2f/UiBAcjuPIJkdzmuf/dSzofBXng3uVKiB4zA4XVbNRBQm7qdxq W4Vp49K9N2PmSenJ7Jdy+oiZhHrAfwv42Ofep1fE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Steven Rostedt (VMware)" Subject: [PATCH 4.9 90/92] tracing: Get trace_array reference for available_tracers files Date: Wed, 16 Oct 2019 14:51:03 -0700 Message-Id: <20191016214848.693341261@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191016214759.600329427@linuxfoundation.org> References: <20191016214759.600329427@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 @@ -3700,9 +3700,14 @@ 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; @@ -3710,6 +3715,14 @@ 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) @@ -3740,8 +3753,8 @@ 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