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 21E2EECE599 for ; Wed, 16 Oct 2019 22:12:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE27E21925 for ; Wed, 16 Oct 2019 22:12:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571263924; bh=sEtzKRnmJWXm1i7t+fTOk3/ruudXpNOfhncm3fa4dOE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=y+JAYnb7HriA3XOiR58zrFYMSPvlqfLx4Bxv6fTdZ6ffkuyC5F2FLv/UAURAJDuLS Ysqz74baOukJFpSp1S7ux6x1DIfBcGW3Zrrojwb2UvKDaUsbHvtmzgFOo0tqRSbTB/ zrNAjgH76hD4ruHgQwe46EEwJWA/sbA1NIDw76zE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439226AbfJPWL6 (ORCPT ); Wed, 16 Oct 2019 18:11:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:48426 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391390AbfJPV4g (ORCPT ); Wed, 16 Oct 2019 17:56:36 -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 3A58321A4C; Wed, 16 Oct 2019 21:56:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571262995; bh=sEtzKRnmJWXm1i7t+fTOk3/ruudXpNOfhncm3fa4dOE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0ZDKWiFSQBwBicPwbXW+pEFgPFghgFYX1jpiWm6F11Y0XV4mg29A1FFTHUo3oue/Z eeKsSirLrLqckftLYAo56u7+B6MzKc9rt4nXk7Hz7dU2hvQKu5mA/PieGDmB5QV912 KY7RO6oXvFLTKFNCgWOUbHiotlvCQFodAXMnHycI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Steven Rostedt (VMware)" Subject: [PATCH 4.14 63/65] tracing: Get trace_array reference for available_tracers files Date: Wed, 16 Oct 2019 14:51:17 -0700 Message-Id: <20191016214840.268456520@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191016214756.457746573@linuxfoundation.org> References: <20191016214756.457746573@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 @@ -4152,9 +4152,14 @@ 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; @@ -4162,6 +4167,14 @@ 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) @@ -4192,8 +4205,8 @@ 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