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From: Vasily Averin <vvs@virtuozzo.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Network Development <netdev@vger.kernel.org>
Subject: Re: [PATCH] net: check skb partial checksum offset after trim
Date: Sun, 13 Dec 2020 22:37:14 +0300	[thread overview]
Message-ID: <98675d3c-62fb-e175-60d6-c1c9964af295@virtuozzo.com> (raw)
In-Reply-To: <CA+FuTScG1iW6nBLxNSLrTXfxxg66-PTu3_5GpKdM+h2HjjY6KA@mail.gmail.com>

On 12/13/20 2:49 AM, Willem de Bruijn wrote:
> On Sat, Dec 12, 2020 at 5:01 AM Vasily Averin <vvs@virtuozzo.com> wrote:
>>
>> On 12/11/20 6:37 PM, Vasily Averin wrote:
>>> It seems for me the similar problem can happen in __skb_trim_rcsum().
>>> Also I doubt that that skb_checksum_start_offset(skb) checks in
>>> __skb_postpull_rcsum() and skb_csum_unnecessary() are correct,
>>> becasue they do not guarantee that skb have correct CHECKSUM_PARTIAL.
>>> Could somebody confirm it?
>>
>> I've rechecked the code and I think now that other places are not affected,
>> i.e. skb_push_rcsum() only should be patched.
> 
> Thanks for investigating this. So tun was able to insert a packet with
> csum_start + csum_off + 2 beyond the packet after trimming, using
> virtio_net_hdr.csum_...
> 
> Any packet with an offset beyond the end of the packet is bogus
> really. No need to try to accept it by downgrading to CHECKSUM_NONE.

Do you mean it's better to force pskb_trim_rcsum() to return -EINVAL instead?

Thank you,
	Vasily Averin

  reply	other threads:[~2020-12-13 19:38 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-11 15:00 [PATCH] net: check skb partial checksum offset after trim Vasily Averin
2020-12-11 15:37 ` Vasily Averin
2020-12-12  8:29   ` Vasily Averin
2020-12-12 23:49     ` Willem de Bruijn
2020-12-13 19:37       ` Vasily Averin [this message]
2020-12-14  1:59         ` Willem de Bruijn
2020-12-14 19:07           ` [PATCH v2] net: drop bogus skb with CHECKSUM_PARTIAL and offset beyond end of trimmed packet Vasily Averin
2020-12-14 20:59             ` Willem de Bruijn
2020-12-15  3:10             ` patchwork-bot+netdevbpf
2020-12-14 20:54           ` [PATCH] net: check skb partial checksum offset after trim Jakub Kicinski
2020-12-14 21:07             ` Willem de Bruijn
2020-12-15  5:42               ` Vasily Averin

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