From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlastimil Babka Subject: Re: [PATCH] netfilter/x_tables: do not fail xt_alloc_table_info too easilly Date: Wed, 8 Aug 2018 10:16:01 +0200 Message-ID: References: <20180807195400.23687-1-mhocko@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: 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, Michal Hocko To: Michal Hocko , Florian Westphal Return-path: In-Reply-To: <20180807195400.23687-1-mhocko@kernel.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 IIRC According to Florian there are more places like this in the netfilter code?