From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [nft PATCH] libnftables: Fix for multiple context instances Date: Mon, 20 Nov 2017 13:37:26 +0100 Message-ID: <20171120123726.GA17459@salvia> References: <20171116191024.18908-1-phil@nwl.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netfilter-devel@vger.kernel.org To: Phil Sutter Return-path: Received: from mail.us.es ([193.147.175.20]:60964 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751083AbdKTMhb (ORCPT ); Mon, 20 Nov 2017 07:37:31 -0500 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id CC9E554D5F6 for ; Mon, 20 Nov 2017 13:37:29 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id BCF9977D8E for ; Mon, 20 Nov 2017 13:37:29 +0100 (CET) Content-Disposition: inline In-Reply-To: <20171116191024.18908-1-phil@nwl.cc> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Thu, Nov 16, 2017 at 08:10:24PM +0100, Phil Sutter wrote: > If a second context is created, the second call to nft_ctx_free() leads > to freeing invalid pointers in nft_exit(). Fix this by introducing a > reference counter so that neither nft_init() nor nft_exit() run more > than once in a row. > > This reference counter has to be protected from parallel access. Do this > using a mutex in a way that once nft_init() returns, the first call to > that function running in parallel is guaranteed to be finished - > otherwise it could happen that things being initialized in one thread > are already accessed in another one. I would prefer this table is placed into the context object, so they are not global anymore. So I would prefer we fix this the right way(tm). Let me know your thoughts, thanks!