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author | Xie He <xie.he.0141@gmail.com> | 2020-08-13 11:17:04 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2020-08-14 20:41:08 -0700 |
commit | 77b981c82c1df7c7ad32a046f17f007450b46954 (patch) | |
tree | d9f759574656a420590b3efd821dc7e607823aad /drivers/net/wan/hdlc_x25.c | |
parent | 4ca0d9ac3fd8f9f90b72a15d8da2aca3ffb58418 (diff) | |
download | linux-stable-77b981c82c1df7c7ad32a046f17f007450b46954.tar.gz linux-stable-77b981c82c1df7c7ad32a046f17f007450b46954.tar.bz2 linux-stable-77b981c82c1df7c7ad32a046f17f007450b46954.zip |
drivers/net/wan/hdlc_x25: Added needed_headroom and a skb->len check
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@gmail.com>
Cc: Martin Schiller <ms@dev.tdt.de>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/wan/hdlc_x25.c')
-rw-r--r-- | drivers/net/wan/hdlc_x25.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/drivers/net/wan/hdlc_x25.c b/drivers/net/wan/hdlc_x25.c index f70336bb6f52..f52b9fed0593 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); |