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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED 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 DD3C7C28CF6 for ; Wed, 25 Jul 2018 01:16:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CB0220883 for ; Wed, 25 Jul 2018 01:16:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="tfMwwEnV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8CB0220883 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388679AbeGYC0G (ORCPT ); Tue, 24 Jul 2018 22:26:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:38926 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388534AbeGYC0G (ORCPT ); Tue, 24 Jul 2018 22:26:06 -0400 Received: from devbox (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 4CE2A20893; Wed, 25 Jul 2018 01:16:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1532481416; bh=8jsm3x+4AMDhBpr2odJLzRortzo+22o+RUvtYhI3ZE0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=tfMwwEnVbGHNXzKeVnzzsNweZG0/2ZxxO/PIg1E63RyG49UyWWkZRFxI1dROjDr3p 6jZRQfgn36cYfTixFScZgUkUuaIeMicvZirwUmVxA+GxHwfrNQZiiCMuOrEYaHwPeR a+KXxf4+odkzULNmeXJ20sy4CslzX342/hauOzgY= Date: Wed, 25 Jul 2018 10:16:53 +0900 From: Masami Hiramatsu To: Steven Rostedt Cc: Tom Zanussi , Masami Hiramatsu , Ingo Molnar , Shuah Khan , Hiraku Toyooka , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/3] [BUGFIX] tracing: Fix double free of event_trigger_data Message-Id: <20180725101653.09e095092a4bb77e6fc558df@kernel.org> In-Reply-To: <20180724191331.738eb819@gandalf.local.home> References: <153149923649.11274.14970833360963898112.stgit@devbox> <153149926702.11274.12489440326560729788.stgit@devbox> <20180723221006.60cc7aa9@vmware.local.home> <20180725000909.6c8b2f3881ee75c4f6bd466b@kernel.org> <20180724164959.3cbc1422@gandalf.local.home> <20180724173008.454cdf10@gandalf.local.home> <20180724191331.738eb819@gandalf.local.home> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 24 Jul 2018 19:13:31 -0400 Steven Rostedt wrote: > On Tue, 24 Jul 2018 17:30:08 -0400 > Steven Rostedt wrote: > > > I don't see where ->reg() would return anything but 1 on success. Maybe > > I'm missing something. I'll look some more, but I'm thinking of changing > > ->reg() to return zero on all success, and negative on all errors and > > just check those results. > > Yeah, I'm going to make these changes. That is, all struct > event_command .reg functions will return negative on error, and > zero or positive on everything else. All the checks are going to be > only for the negative value. > > But for the bug fix itself, I believe this should do it. Masami, what > do you think? Hm, as far as I can see, when register_trigger() returns >= 0, it already calls ->init the trigger_data. This means its refcount++, and in that case, below patch will miss to free the trigger_data. How about below for tentative fix? if (!ret) { ret = -ENOENT; /* We have to forcibly free the trigger_data */ goto out_free; } else if (ret > 0) ret = 0; Thank you, > > -- Steve > > diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c > index d18249683682..8771a27ca60f 100644 > --- a/kernel/trace/trace_events_trigger.c > +++ b/kernel/trace/trace_events_trigger.c > @@ -679,6 +679,8 @@ event_trigger_callback(struct event_command *cmd_ops, > goto out_free; > > out_reg: > + /* Up the trigger_data count to make sure reg doesn't free it on failure */ > + event_trigger_init(trigger_ops, trigger_data); > ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file); > /* > * The above returns on success the # of functions enabled, > @@ -687,10 +689,11 @@ event_trigger_callback(struct event_command *cmd_ops, > */ > if (!ret) { > ret = -ENOENT; > - goto out_free; > - } else if (ret < 0) > - goto out_free; > - ret = 0; > + } else if (ret > 0) > + ret = 0; > + > + /* Down the counter of trigger_data or free it if not used anymore */ > + event_trigger_free(trigger_ops, trigger_data); > out: > return ret; > -- Masami Hiramatsu