From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 7DF9D6B0003 for ; Wed, 8 Aug 2018 04:25:16 -0400 (EDT) Received: by mail-pl0-f69.google.com with SMTP id u2-v6so1091980pls.7 for ; Wed, 08 Aug 2018 01:25:16 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id l5-v6si3377992pff.304.2018.08.08.01.25.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 Aug 2018 01:25:15 -0700 (PDT) Date: Wed, 8 Aug 2018 10:25:11 +0200 From: Michal Hocko Subject: Re: [PATCH] netfilter/x_tables: do not fail xt_alloc_table_info too easilly Message-ID: <20180808082511.GF27972@dhcp22.suse.cz> References: <20180807195400.23687-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Florian Westphal , Georgi Nikolov , Andrew Morton , "David S. Miller" , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Wed 08-08-18 10:16:01, Vlastimil Babka wrote: > On 08/07/2018 09:54 PM, Michal Hocko wrote: > > From: Michal Hocko > > > > eacd86ca3b03 ("net/netfilter/x_tables.c: use kvmalloc() > > in xt_alloc_table_info()") has unintentionally fortified > > xt_alloc_table_info allocation when __GFP_RETRY has been dropped from > > the vmalloc fallback. Later on there was a syzbot report that this > > can lead to OOM killer invocations when tables are too large and > > 0537250fdc6c ("netfilter: x_tables: make allocation less aggressive") > > has been merged to restore the original behavior. Georgi Nikolov however > > noticed that he is not able to install his iptables anymore so this can > > be seen as a regression. > > > > The primary argument for 0537250fdc6c was that this allocation path > > shouldn't really trigger the OOM killer and kill innocent tasks. On the > > other hand the interface requires root and as such should allow what the > > admin asks for. Root inside a namespaces makes this more complicated > > because those might be not trusted in general. If they are not then such > > namespaces should be restricted anyway. Therefore drop the __GFP_NORETRY > > and replace it by __GFP_ACCOUNT to enfore memcg constrains on it. > > > > Fixes: 0537250fdc6c ("netfilter: x_tables: make allocation less aggressive") > > Reported-by: Georgi Nikolov > > Suggested-by: Vlastimil Babka > > Acked-by: Florian Westphal > > Signed-off-by: Michal Hocko > > Acked-by: Vlastimil Babka Thanks! > IIRC According to Florian there are more places like this in the > netfilter code? Well, this is more for netfilter guys. I can only give a general guidance that generally untrusted allocations triggered from userspace should be a subject of kmem accounting. -- Michal Hocko SUSE Labs