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
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.
Cc: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Cc: Martin Schiller <m...@dev.tdt.de>
Signed-off-by: Xie He <xie.he.0...@gmail.com>
---
drivers/net/wan/x25_asy.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
index 84640a0c13f3..de7984463595 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -307,6 +307,14 @@ static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
return NETDEV_TX_OK;
}
+ /* 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;
+ }
+
switch (skb->data[0]) {
case X25_IFACE_DATA:
break;
@@ -752,6 +760,12 @@ static void x25_asy_setup(struct net_device *dev)
dev->type = ARPHRD_X25;
dev->tx_queue_len = 10;
+ /* When transmitting data:
+ * first this driver removes a pseudo header of 1 byte,
+ * then the lapb module prepends an LAPB header of at most 3 bytes.
+ */
+ dev->needed_headroom = 3 - 1;
+
/* New-style flags. */
dev->flags = IFF_NOARP;
}
--
2.25.1
