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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 24362C433F5 for ; Fri, 3 Sep 2021 04:03:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B01F603E9 for ; Fri, 3 Sep 2021 04:03:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229590AbhICED7 (ORCPT ); Fri, 3 Sep 2021 00:03:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:38708 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231872AbhICEDs (ORCPT ); Fri, 3 Sep 2021 00:03:48 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 58F3960E77; Fri, 3 Sep 2021 04:02:48 +0000 (UTC) Date: Fri, 3 Sep 2021 00:02:46 -0400 From: Steven Rostedt To: Jiang Jiasheng Cc: mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] tracing: Add trace_trigger_soft_disabled() in front of trace_event_buffer_reserve() in trace_inject_entry() Message-ID: <20210903000246.425731d5@oasis.local.home> In-Reply-To: <1630639834-767471-1-git-send-email-jiasheng@iscas.ac.cn> References: <1630639834-767471-1-git-send-email-jiasheng@iscas.ac.cn> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 3 Sep 2021 03:30:34 +0000 Jiang Jiasheng wrote: > Directly use trace_event_buffer_reserve() might be unsafe, How can it be unsafe? > as we can see from the trace_trigger_soft_disabled() of > 'include/linux/trace_events.h' that if the value of > file->flags is 256, the check in the trace_trigger_soft_disabled() > will be passed but actually shouldn't have. > Therefore, we suggest that trace_trigger_soft_disabled() > should be added in front of the trace_event_buffer_reserve() > in trace_inject_entry(). Do you understand what the trace_inject_entry() does? I'm not sure it makes sense to "soft disable" it. > > Signed-off-by: Jiang Jiasheng > --- > kernel/trace/trace_events_inject.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/trace/trace_events_inject.c b/kernel/trace/trace_events_inject.c > index c188045..6dfd3cd 100644 > --- a/kernel/trace/trace_events_inject.c > +++ b/kernel/trace/trace_events_inject.c > @@ -21,6 +21,8 @@ trace_inject_entry(struct trace_event_file *file, void *rec, int len) > void *entry; > > rcu_read_lock_sched(); > + if (trace_trigger_soft_disabled(file)) > + return written; NACK! The above introduces a major bug. Bonus points if you can figure out what that is yourself. -- Steve > entry = trace_event_buffer_reserve(&fbuffer, file, len); > if (entry) { > memcpy(entry, rec, len);