netdev - Re: [PATCH net] skbuff: fix incorrect msg

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Message-ID: <e9b3d5a9-96b4-f857-e9b8-82f1e3c49c1d@gmail.com>
Date:   Thu, 10 Jun 2021 16:03:05 +0200
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, soheil@...gle.com,
        jonathan.lemon@...il.com, Willem de Bruijn <willemb@...gle.com>,
        Talal Ahmad <talalahmad@...gle.com>
Subject: Re: [PATCH net] skbuff: fix incorrect msg_zerocopy copy notifications



On 6/10/21 12:41 AM, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
> 
> msg_zerocopy signals if a send operation required copying with a flag
> in serr->ee.ee_code.
> 
> This field can be incorrect as of the below commit, as a result of
> both structs uarg and serr pointing into the same skb->cb[].
> 
> uarg->zerocopy must be read before skb->cb[] is reinitialized to hold
> serr. Similar to other fields len, hi and lo, use a local variable to
> temporarily hold the value.
> 
> This was not a problem before, when the value was passed as a function
> argument.
> 
> Fixes: 75518851a2a0 ("skbuff: Push status and refcounts into sock_zerocopy_callback")
> Reported-by: Talal Ahmad <talalahmad@...gle.com>
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>
> ---


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