| Message ID | 20201020013152.89259-1-xie.he.0141@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] net: hdlc: In hdlc_rcv, check to make sure dev is an HDLC device | expand |
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@pm.waw.pl> > Signed-off-by: Xie He <xie.he.0141@gmail.com> Applied, thank you!
diff --git a/drivers/net/wan/hdlc.c b/drivers/net/wan/hdlc.c index 9b00708676cf..1bdd3df0867a 100644 --- a/drivers/net/wan/hdlc.c +++ b/drivers/net/wan/hdlc.c @@ -46,7 +46,15 @@ static struct hdlc_proto *first_proto; static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *p, struct net_device *orig_dev) { - struct hdlc_device *hdlc = dev_to_hdlc(dev); + struct hdlc_device *hdlc; + + /* First make sure "dev" is an HDLC device */ + if (!(dev->priv_flags & IFF_WAN_HDLC)) { + kfree_skb(skb); + return NET_RX_SUCCESS; + } + + hdlc = dev_to_hdlc(dev); if (!net_eq(dev_net(dev), &init_net)) { kfree_skb(skb);
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@pm.waw.pl> Signed-off-by: Xie He <xie.he.0141@gmail.com> --- drivers/net/wan/hdlc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)