From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [Patch net] net_sched: fix a memory leak of filter chain Date: Wed, 6 Sep 2017 09:38:39 +0200 Message-ID: <20170906073839.GD2523@nanopsycho> References: <20170906050310.26474-1-xiyou.wangcong@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, jakub.kicinski@netronome.com, Jiri Pirko To: Cong Wang Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:34752 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751737AbdIFHim (ORCPT ); Wed, 6 Sep 2017 03:38:42 -0400 Received: by mail-wm0-f66.google.com with SMTP id l19so1691793wmi.1 for ; Wed, 06 Sep 2017 00:38:41 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20170906050310.26474-1-xiyou.wangcong@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Wed, Sep 06, 2017 at 07:03:10AM CEST, xiyou.wangcong@gmail.com wrote: >tcf_chain_destroy() is called by tcf_block_put() and tcf_chain_put(). >tcf_chain_put() is refcn'ed and paired with tcf_chain_get(), >but tcf_block_put() is not, it should be paired with tcf_block_get() >and we still need to decrease the refcnt. However, tcf_block_put() >is special, it stores the chains too, we have to detach them if >it is not the last user. You don't describe the original issue, or I am missing that from your description. > >What's more, index 0 is not special at all, it should be treated >like other chains. This also makes the code more readable. [...] >@@ -246,10 +246,7 @@ EXPORT_SYMBOL(tcf_chain_get); > > void tcf_chain_put(struct tcf_chain *chain) > { >- /* Destroy unused chain, with exception of chain 0, which is the >- * default one and has to be always present. >- */ >- if (--chain->refcnt == 0 && !chain->filter_chain && chain->index != 0) >+ if (--chain->refcnt == 0) The refcounting is only done for actions holding reference to the chain. You still need to check is the filter chain is not empty. See tc_ctl_tfilter. Also, chain 0 is created by default on a block creation. It has to be present always for a reason. Please see tcf_block_get. The pointer to chain 0 is assigned to the qdisc filter list pointer. > tcf_chain_destroy(chain); > } > EXPORT_SYMBOL(tcf_chain_put); >@@ -296,8 +293,11 @@ void tcf_block_put(struct tcf_block *block) > > list_for_each_entry_safe(chain, tmp, &block->chain_list, list) { > tcf_chain_flush(chain); >- tcf_chain_destroy(chain); >+ tcf_chain_put(chain); > } >+ /* If tc actions still hold the chain, just detach it. */ >+ list_for_each_entry_safe(chain, tmp, &block->chain_list, list) >+ tcf_chain_detach(chain); > kfree(block); > } > EXPORT_SYMBOL(tcf_block_put); >-- >2.13.0 >