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Subject: Re: [PATCH] netfilter/x_tables: do not fail xt_alloc_table_info too
 easilly
To:     Michal Hocko <mhocko@kernel.org>, Florian Westphal <fw@strlen.de>
Cc:     Georgi Nikolov <gnikolov@icdsoft.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Michal Hocko <mhocko@suse.com>
References: <20180807195400.23687-1-mhocko@kernel.org>
From:   Vlastimil Babka <vbabka@suse.cz>
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Message-ID: <a060e57c-dbcd-d3bc-c975-ac8a66468666@suse.cz>
Date:   Wed, 8 Aug 2018 10:16:01 +0200
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On 08/07/2018 09:54 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 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 <gnikolov@icdsoft.com>
> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
> Acked-by: Florian Westphal <fw@strlen.de>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

IIRC According to Florian there are more places like this in the
netfilter code?