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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 9276AC28CF6 for ; Wed, 25 Jul 2018 02:41:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47E2720883 for ; Wed, 25 Jul 2018 02:41:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 47E2720883 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.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 S2388547AbeGYDvU (ORCPT ); Tue, 24 Jul 2018 23:51:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:52356 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388464AbeGYDvU (ORCPT ); Tue, 24 Jul 2018 23:51:20 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (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 BFA6920856; Wed, 25 Jul 2018 02:41:51 +0000 (UTC) Date: Tue, 24 Jul 2018 22:41:49 -0400 From: Steven Rostedt To: Masami Hiramatsu Cc: Tom Zanussi , 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: <20180724224149.0767fd13@gandalf.local.home> In-Reply-To: <20180725101653.09e095092a4bb77e6fc558df@kernel.org> 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> <20180725101653.09e095092a4bb77e6fc558df@kernel.org> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-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 Wed, 25 Jul 2018 10:16:53 +0900 Masami Hiramatsu wrote: > 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; Or better yet, match it properly: 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, * but if it didn't find any functions it returns zero. * Consider no functions a failure too. */ if (!ret) { cmd_ops->unreg(glob, trigger_ops, trigger_data, file); ret = -ENOENT; } 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; -- Steve