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From: Dmitry Vyukov <dvyukov@google.com>
Date: Mon, 30 Nov 2015 15:16:27 +0100
Message-ID: <CACT4Y+YXEfpE4wa1byedf6m2iqzVsx6V6r7FEDiLw0WKRmA0Ew@mail.gmail.com>
Subject: Re: [PATCH net] bpf: fix allocation warnings in bpf maps and integer overflow
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: syzkaller <syzkaller@googlegroups.com>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        David Miller <davem@davemloft.net>,
        Alexei Starovoitov <ast@kernel.org>, netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Kostya Serebryany <kcc@google.com>,
        Alexander Potapenko <glider@google.com>,
        Eric Dumazet <edumazet@google.com>,
        Sasha Levin <sasha.levin@oracle.com>
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On Mon, Nov 30, 2015 at 3:13 PM, Daniel Borkmann <daniel@iogearbox.net> wrote:
> On 11/30/2015 02:57 PM, Dmitry Vyukov wrote:
> ...
>>
>> kamlloc produces a WARNING if you try to allocate more than it ever
>> possibly can (KMALLOC_SHIFT_MAX).
>
>
> Sure, I understand that.
>
> The kzalloc() in array_map_alloc() is however with __GFP_NOWARN flag
> already.
> The warning only triggers in mm if:
>
>   WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
>
> Your test case is using ca.map_type = 1, which is BPF_MAP_TYPE_HASH. So on
> update you're triggering the kmalloc() in htab_map_update_elem().
>
> I'm just asking about the added change in array map.


Then, sorry.
Let's wait for Alexei.
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