netdev - Re: [PATCH net v2] net: tun: fix bugs for oversize packet when napi frags enabled

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Date:   Sat, 29 Oct 2022 08:35:11 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Ziyang Xuan <william.xuanziyang@...wei.com>
Cc:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        peterpenkov96@...il.com, maheshb@...gle.com, ast@...nel.org,
        daniel@...earbox.net, hawk@...nel.org, john.fastabend@...il.com
Subject: Re: [PATCH net v2] net: tun: fix bugs for oversize packet when napi
 frags enabled

On Sat, Oct 29, 2022 at 2:41 AM Ziyang Xuan
<william.xuanziyang@...wei.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@...gle.com>