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Date:   Fri, 14 Aug 2020 07:15:29 +0000
From:   linmiaohe <>
To:     Willem de Bruijn <>
CC:     David Miller <>,
        Jakub Kicinski <>,
        Florian Westphal <>,
        "" <>,
        "" <>,
        "" <>,
        Eric Dumazet <>,
        Steffen Klassert <>,
        "Paolo Abeni" <>,
        Shmulik Ladkani <>,
        "Yadu Kishore" <>,
        "" <>,
        Network Development <>,
        linux-kernel <>
Subject: Re: [PATCH] net: add missing skb_uarg refcount increment in

Willem de Bruijn <> wrote:
>On Thu, Aug 13, 2020 at 2:16 PM Miaohe Lin <> wrote:
>> If the skb is zcopied, we should increase the skb_uarg refcount before 
>> we involve skb_release_data(). See pskb_expand_head() as a reference.
>Did you manage to observe a bug through this datapath in practice?
>pskb_carve_inside_header is called
>  from pskb_carve
>    from pskb_extract
>      from rds_tcp_data_recv
>That receive path should not see any packets with zerocopy state associated.

This works fine yet as its caller is limited. But we should take care of the skb_uarg refcount for future use.
On the other hand, because this codepath should not see any packets with zerocopy state associated, then we
should not call skb_orphan_frags here.


>> Fixes: 6fa01ccd8830 ("skbuff: Add pskb_extract() helper function")
>> Signed-off-by: Miaohe Lin <>

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