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References: <20221029094101.1653855-1-william.xuanziyang@huawei.com>
In-Reply-To: <20221029094101.1653855-1-william.xuanziyang@huawei.com>
From:   Eric Dumazet <edumazet@google.com>
Date:   Sat, 29 Oct 2022 08:35:11 -0700
Message-ID: <CANn89iKYgg6o5wQQ+QrKUU6jv7FBejU=xg+jxkTVZb_9CCxReg@mail.gmail.com>
Subject: Re: [PATCH net v2] net: tun: fix bugs for oversize packet when napi
 frags enabled
To:     Ziyang Xuan <william.xuanziyang@huawei.com>
Cc:     davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        peterpenkov96@gmail.com, maheshb@google.com, ast@kernel.org,
        daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com
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On Sat, Oct 29, 2022 at 2:41 AM Ziyang Xuan
<william.xuanziyang@huawei.com> wrote:
>
> Recently, we got two syzkaller problems because of oversize packet
> when napi frags enabled.
>
> One of the problems is because the first seg size of the iov_iter
> from user space is very big, it is 2147479538 which is bigger than
> the threshold value for bail out early in __alloc_pages(). And
> skb->pfmemalloc is true, __kmalloc_reserve() would use pfmemalloc
> reserves without __GFP_NOWARN flag. Thus we got a warning as following:
>
>

Reviewed-by: Eric Dumazet <edumazet@google.com>