Re: [PATCH net v2] net: hdlc: In hdlc_rcv, check to make sure dev is an HDLC device

[Jakub Kicinski]

On Mon, 19 Oct 2020 18:31:52 -0700 Xie He wrote:
> The hdlc_rcv function is used as hdlc_packet_type.func to process any
> skb received in the kernel with skb->protocol == htons(ETH_P_HDLC).
> The purpose of this function is to provide second-stage processing for
> skbs not assigned a "real" L3 skb->protocol value in the first stage.
> 
> This function assumes the device from which the skb is received is an
> HDLC device (a device created by this module). It assumes that
> netdev_priv(dev) returns a pointer to "struct hdlc_device".
> 
> However, it is possible that some driver in the kernel (not necessarily
> in our control) submits a received skb with skb->protocol ==
> htons(ETH_P_HDLC), from a non-HDLC device. In this case, the skb would
> still be received by hdlc_rcv. This will cause problems.
> 
> hdlc_rcv should be able to recognize and drop invalid skbs. It should
> first make sure "dev" is actually an HDLC device, before starting its
> processing. This patch adds this check to hdlc_rcv.
> 
> Cc: Krzysztof Halasa <khc@xxxxxxxxx>
> Signed-off-by: Xie He <xie.he.0141@xxxxxxxxx>

Applied, thank you!