From nobody Sun Sep 14 22:43:21 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76E5AECAAD8 for ; Tue, 13 Sep 2022 17:15:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232681AbiIMRPp (ORCPT ); Tue, 13 Sep 2022 13:15:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232641AbiIMROx (ORCPT ); Tue, 13 Sep 2022 13:14:53 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EC5A1AD8E; Tue, 13 Sep 2022 09:03:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 5E829CE1281; Tue, 13 Sep 2022 14:17:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F8E7C43470; Tue, 13 Sep 2022 14:17:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663078658; bh=VQo1ymelByDOIabi+qMStXzslI1hWPh7/22KgE1kAnA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YjjIa1nXKMsQPiuz88CfdUFwVTG/fL4o5xFqtXJTuDhsrB1ihFz5qEjVfqs9h76A+ cFDFJ0DNhebVssirj0FVY0jv+PCsXBnm5d7SOaVLQD5rzRY43YZr4ZuJn+lKLdmQ5p 6m9rsu0JXLM5QlXvTXMy4248UhZCOExrW1ZLZvz0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Masami Hiramatsu (Google)" , "Steven Rostedt (Google)" Subject: [PATCH 5.15 032/121] tracing: Fix to check event_mutex is held while accessing trigger list Date: Tue, 13 Sep 2022 16:03:43 +0200 Message-Id: <20220913140358.731269290@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140357.323297659@linuxfoundation.org> References: <20220913140357.323297659@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Masami Hiramatsu (Google) commit cecf8e128ec69149fe53c9a7bafa505a4bee25d9 upstream. Since the check_user_trigger() is called outside of RCU read lock, this list_for_each_entry_rcu() caused a suspicious RCU usage warning. # echo hist:keys=3Dpid > events/sched/sched_stat_runtime/trigger # cat events/sched/sched_stat_runtime/trigger [ 43.167032] [ 43.167418] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D [ 43.167992] WARNING: suspicious RCU usage [ 43.168567] 5.19.0-rc5-00029-g19ebe4651abf #59 Not tainted [ 43.169283] ----------------------------- [ 43.169863] kernel/trace/trace_events_trigger.c:145 RCU-list traversed i= n non-reader section!! ... However, this file->triggers list is safe when it is accessed under event_mutex is held. To fix this warning, adds a lockdep_is_held check to the list_for_each_entry_rcu(). Link: https://lkml.kernel.org/r/166226474977.223837.1992182913048377113.stg= it@devnote2 Cc: stable@vger.kernel.org Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events") Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_events_trigger.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -128,7 +128,8 @@ static bool check_user_trigger(struct tr { struct event_trigger_data *data; =20 - list_for_each_entry_rcu(data, &file->triggers, list) { + list_for_each_entry_rcu(data, &file->triggers, list, + lockdep_is_held(&event_mutex)) { if (data->flags & EVENT_TRIGGER_FL_PROBE) continue; return true;