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=-4.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_DBL_ABUSE_MALW autolearn=no 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 0006FC2D0DB for ; Thu, 30 Jan 2020 14:48:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B819324685 for ; Thu, 30 Jan 2020 14:48:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727487AbgA3OsN (ORCPT ); Thu, 30 Jan 2020 09:48:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:33500 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727247AbgA3OsM (ORCPT ); Thu, 30 Jan 2020 09:48:12 -0500 Received: from gandalf.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 D926824681; Thu, 30 Jan 2020 14:48:11 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.93) (envelope-from ) id 1ixB74-001CL9-Pb; Thu, 30 Jan 2020 09:48:10 -0500 Message-Id: <20200130144810.669688514@goodmis.org> User-Agent: quilt/0.65 Date: Thu, 30 Jan 2020 09:47:46 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , stable@vger.kernel.org, "Joel Fernandes (Google)" , Peter Zijlstra , Thomas Gleixner , "Paul E. McKenney" , syzbot+774fddf07b7ab29a1e55@syzkaller.appspotmail.com, Mathieu Desnoyers Subject: [for-next][PATCH 03/21] tracing: Fix sched switch start/stop refcount racy updates References: <20200130144743.527378179@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mathieu Desnoyers Reading the sched_cmdline_ref and sched_tgid_ref initial state within tracing_start_sched_switch without holding the sched_register_mutex is racy against concurrent updates, which can lead to tracepoint probes being registered more than once (and thus trigger warnings within tracepoint.c). [ May be the fix for this bug ] Link: https://lore.kernel.org/r/000000000000ab6f84056c786b93@google.com Link: http://lkml.kernel.org/r/20190817141208.15226-1-mathieu.desnoyers@efficios.com Cc: stable@vger.kernel.org CC: Steven Rostedt (VMware) CC: Joel Fernandes (Google) CC: Peter Zijlstra CC: Thomas Gleixner CC: Paul E. McKenney Reported-by: syzbot+774fddf07b7ab29a1e55@syzkaller.appspotmail.com Fixes: d914ba37d7145 ("tracing: Add support for recording tgid of tasks") Signed-off-by: Mathieu Desnoyers Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_sched_switch.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c index e288168661e1..e304196d7c28 100644 --- a/kernel/trace/trace_sched_switch.c +++ b/kernel/trace/trace_sched_switch.c @@ -89,8 +89,10 @@ static void tracing_sched_unregister(void) static void tracing_start_sched_switch(int ops) { - bool sched_register = (!sched_cmdline_ref && !sched_tgid_ref); + bool sched_register; + mutex_lock(&sched_register_mutex); + sched_register = (!sched_cmdline_ref && !sched_tgid_ref); switch (ops) { case RECORD_CMDLINE: -- 2.24.1