linux-kernel - Re: [PATCH net-next v6 4/5] net: hdlc_fr: Improve the initial checks when we receive an skb

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Date:   Sat, 31 Oct 2020 10:25:49 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Xie He <xie.he.0141@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Network Development <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Krzysztof Halasa <khc@...waw.pl>
Subject: Re: [PATCH net-next v6 4/5] net: hdlc_fr: Improve the initial checks
 when we receive an skb

On Fri, Oct 30, 2020 at 8:49 PM Xie He <xie.he.0141@...il.com> wrote:
>
> 1.
> Change the skb->len check from "<= 4" to "< 4".
> At first we only need to ensure a 4-byte header is present. We indeed
> normally need the 5th byte, too, but it'd be more logical and cleaner
> to check its existence when we actually need it.
>
> 2.
> Add an fh->ea2 check to the initial checks in fr_rx. fh->ea2 == 1 means
> the second address byte is the final address byte. We only support the
> case where the address length is 2 bytes. If the address length is not
> 2 bytes, the control field and the protocol field would not be the 3rd
> and 4th byte as we assume. (Say it is 3 bytes, then the control field
> and the protocol field would be the 4th and 5th byte instead.)
>
> Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>
> Cc: Krzysztof Halasa <khc@...waw.pl>
> Signed-off-by: Xie He <xie.he.0141@...il.com>

Acked-by: Willem de Bruijn <willemb@...gle.com>