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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 076F0C35242 for ; Fri, 24 Jan 2020 07:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7C7A2071A for ; Fri, 24 Jan 2020 07:03:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730253AbgAXHDP (ORCPT ); Fri, 24 Jan 2020 02:03:15 -0500 Received: from relay.sw.ru ([185.231.240.75]:53118 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726695AbgAXHDL (ORCPT ); Fri, 24 Jan 2020 02:03:11 -0500 Received: from vvs-ws.sw.ru ([172.16.24.21]) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1iuszT-00085s-Uh; Fri, 24 Jan 2020 10:02:52 +0300 From: Vasily Averin Subject: [PATCH 3/7] t_next should increase position index To: linux-kernel@vger.kernel.org Cc: Andrew Morton , NeilBrown , Waiman Long , Steven Rostedt , Ingo Molnar , Peter Oberparleiter Message-ID: <8681248a-da16-5448-31fe-26df9e7cfc25@virtuozzo.com> Date: Fri, 24 Jan 2020 10:02:51 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin --- kernel/trace/ftrace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9bf1f2c..ca25210 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3442,8 +3442,10 @@ static void *t_mod_start(struct seq_file *m, loff_t *pos) loff_t l = *pos; /* t_probe_start() must use original pos */ void *ret; - if (unlikely(ftrace_disabled)) + if (unlikely(ftrace_disabled)) { + (*pos)++; return NULL; + } if (iter->flags & FTRACE_ITER_PROBE) return t_probe_next(m, pos); -- 1.8.3.1