From: Xie He <xie.he.0141@xxxxxxxxx>
[ Upstream commit 77b981c82c1df7c7ad32a046f17f007450b46954 ]
1. Added a skb->len check
This driver expects upper layers to include a pseudo header of 1 byte
when passing down a skb for transmission. This driver will read this
1-byte header. This patch added a skb->len check before reading the
header to make sure the header exists.
2. Added needed_headroom and set hard_header_len to 0
When this driver transmits data,
first this driver will remove a pseudo header of 1 byte,
then the lapb module will prepend the LAPB header of 2 or 3 bytes.
So the value of needed_headroom in this driver should be 3 - 1.
Because this driver has no header_ops, according to the logic of
af_packet.c, the value of hard_header_len should be 0.
Reason of setting needed_headroom and hard_header_len at this place:
This driver is written using the API of the hdlc module, the hdlc
module enables this driver (the protocol driver) to run on any hardware
that has a driver (the hardware driver) written using the API of the
hdlc module.
Two other hdlc protocol drivers - hdlc_ppp and hdlc_raw_eth, also set
things like hard_header_len at this place. In hdlc_ppp, it sets
hard_header_len after attach_hdlc_protocol and before setting dev->type.
In hdlc_raw_eth, it sets hard_header_len by calling ether_setup after
attach_hdlc_protocol and after memcpy the settings.
3. Reset needed_headroom when detaching protocols (in hdlc.c)
When detaching a protocol from a hardware device, the hdlc module will
reset various parameters of the device (including hard_header_len) to
the default values. We add needed_headroom here so that needed_headroom
will also be reset.
Cc: Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx>
Cc: Martin Schiller <ms@xxxxxxxxxx>
Cc: Andrew Hendry <andrew.hendry@xxxxxxxxx>
Signed-off-by: Xie He <xie.he.0141@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/wan/hdlc.c | 1 +
drivers/net/wan/hdlc_x25.c | 17 ++++++++++++++++-
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wan/hdlc.c b/drivers/net/wan/hdlc.c
index dfc16770458d8..386ed2aa31fd9 100644
--- a/drivers/net/wan/hdlc.c
+++ b/drivers/net/wan/hdlc.c
@@ -230,6 +230,7 @@ static void hdlc_setup_dev(struct net_device *dev)
dev->max_mtu = HDLC_MAX_MTU;
dev->type = ARPHRD_RAWHDLC;
dev->hard_header_len = 16;
+ dev->needed_headroom = 0;
dev->addr_len = 0;
dev->header_ops = &hdlc_null_ops;
}
diff --git a/drivers/net/wan/hdlc_x25.c b/drivers/net/wan/hdlc_x25.c
index f70336bb6f524..f52b9fed05931 100644
--- a/drivers/net/wan/hdlc_x25.c
+++ b/drivers/net/wan/hdlc_x25.c
@@ -107,8 +107,14 @@ static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev)
{
int result;
+ /* There should be a pseudo header of 1 byte added by upper layers.
+ * Check to make sure it is there before reading it.
+ */
+ if (skb->len < 1) {
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
+ }
- /* X.25 to LAPB */
switch (skb->data[0]) {
case X25_IFACE_DATA: /* Data to be transmitted */
skb_pull(skb, 1);
@@ -294,6 +300,15 @@ static int x25_ioctl(struct net_device *dev, struct ifreq *ifr)
return result;
memcpy(&state(hdlc)->settings, &new_settings, size);
+
+ /* There's no header_ops so hard_header_len should be 0. */
+ dev->hard_header_len = 0;
+ /* When transmitting data:
+ * first we'll remove a pseudo header of 1 byte,
+ * then we'll prepend an LAPB header of at most 3 bytes.
+ */
+ dev->needed_headroom = 3 - 1;
+
dev->type = ARPHRD_X25;
call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
netif_dormant_off(dev);
--
2.25.1
