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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 B948CC2D0DB for ; Fri, 31 Jan 2020 22:08:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 945CD2082E for ; Fri, 31 Jan 2020 22:08:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726262AbgAaWIK (ORCPT ); Fri, 31 Jan 2020 17:08:10 -0500 Received: from Chamillionaire.breakpoint.cc ([193.142.43.52]:52746 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726163AbgAaWIK (ORCPT ); Fri, 31 Jan 2020 17:08:10 -0500 Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1ixeSN-00060X-O8; Fri, 31 Jan 2020 23:08:07 +0100 Date: Fri, 31 Jan 2020 23:08:07 +0100 From: Florian Westphal To: Cong Wang Cc: netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com, Pablo Neira Ayuso , Jozsef Kadlecsik , Florian Westphal Subject: Re: [Patch nf 3/3] xt_hashlimit: limit the max size of hashtable Message-ID: <20200131220807.GJ795@breakpoint.cc> References: <20200131205216.22213-1-xiyou.wangcong@gmail.com> <20200131205216.22213-4-xiyou.wangcong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200131205216.22213-4-xiyou.wangcong@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Cong Wang wrote: > The user-specified hashtable size is unbound, this could > easily lead to an OOM or a hung task as we hold the global > mutex while allocating and initializing the new hashtable. > > The max value is derived from the max value when chosen by > the kernel. > > Reported-and-tested-by: syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com > Cc: Pablo Neira Ayuso > Cc: Jozsef Kadlecsik > Cc: Florian Westphal > Signed-off-by: Cong Wang > --- > net/netfilter/xt_hashlimit.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c > index 57a2639bcc22..6327134c5886 100644 > --- a/net/netfilter/xt_hashlimit.c > +++ b/net/netfilter/xt_hashlimit.c > @@ -272,6 +272,8 @@ dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent) > } > static void htable_gc(struct work_struct *work); > > +#define HASHLIMIT_MAX_SIZE 8192 > + > static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg, > const char *name, u_int8_t family, > struct xt_hashlimit_htable **out_hinfo, > @@ -290,7 +292,7 @@ static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg, > size = (nr_pages << PAGE_SHIFT) / 16384 / > sizeof(struct hlist_head); > if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE) > - size = 8192; > + size = HASHLIMIT_MAX_SIZE; > if (size < 16) > size = 16; > } > @@ -848,6 +850,8 @@ static int hashlimit_mt_check_common(const struct xt_mtchk_param *par, > > if (cfg->gc_interval == 0 || cfg->expire == 0) > return -EINVAL; > + if (cfg->size > HASHLIMIT_MAX_SIZE) > + return -ENOMEM; Hmm, won't that break restore of rulesets that have something like --hashlimit-size 10000? AFAIU this limits the module to vmalloc requests of only 64kbyte. I'm not opposed to a limit (or a cap), but 64k seems a bit low to me.