From patchwork Sun Nov 20 20:07:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13050139 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 30214C43219 for ; Sun, 20 Nov 2022 20:07:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229797AbiKTUHo (ORCPT ); Sun, 20 Nov 2022 15:07:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52668 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229751AbiKTUHl (ORCPT ); Sun, 20 Nov 2022 15:07:41 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6B391E729; Sun, 20 Nov 2022 12:07:38 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id EDB4260D39; Sun, 20 Nov 2022 20:07:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6FD6C433D7; Sun, 20 Nov 2022 20:07:36 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1owqbH-00Di9j-2x; Sun, 20 Nov 2022 15:07:35 -0500 Message-ID: <20221120200735.791518959@goodmis.org> User-Agent: quilt/0.66 Date: Sun, 20 Nov 2022 15:07:13 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , Linux Trace Kernel , Tzvetomir Stoyanov , Tom Zanussi , stable@vger.kernel.org, Rafael Mendonca Subject: [for-linus][PATCH 13/13] tracing: Fix race where eprobes can be called before the event References: <20221120200700.725968899@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org From: "Steven Rostedt (Google)" The flag that tells the event to call its triggers after reading the event is set for eprobes after the eprobe is enabled. This leads to a race where the eprobe may be triggered at the beginning of the event where the record information is NULL. The eprobe then dereferences the NULL record causing a NULL kernel pointer bug. Test for a NULL record to keep this from happening. Link: https://lore.kernel.org/linux-trace-kernel/20221116192552.1066630-1-rafaelmendsr@gmail.com/ Link: https://lore.kernel.org/linux-trace-kernel/20221117214249.2addbe10@gandalf.local.home Cc: Linux Trace Kernel Cc: Tzvetomir Stoyanov Cc: Tom Zanussi Cc: stable@vger.kernel.org Fixes: 7491e2c442781 ("tracing: Add a probe that attaches to trace events") Acked-by: Masami Hiramatsu (Google) Reported-by: Rafael Mendonca Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_eprobe.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index 5dd0617e5df6..9cda9a38422c 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -563,6 +563,9 @@ static void eprobe_trigger_func(struct event_trigger_data *data, { struct eprobe_data *edata = data->private_data; + if (unlikely(!rec)) + return; + __eprobe_trace_func(edata, rec); }