drivers/net/wan/x25_asy: 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 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.kernel@gmail.com> Cc: Martin Schiller <ms@dev.tdt.de> Signed-off-by: Xie He <xie.he.0141@gmail.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -307,6 +307,14 @@ static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
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return NETDEV_TX_OK;
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return NETDEV_TX_OK;
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}
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}
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/* There should be a pseudo header of 1 byte added by upper layers.
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* Check to make sure it is there before reading it.
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*/
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if (skb->len < 1) {
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kfree_skb(skb);
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return NETDEV_TX_OK;
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}
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switch (skb->data[0]) {
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switch (skb->data[0]) {
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case X25_IFACE_DATA:
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case X25_IFACE_DATA:
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break;
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break;
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@ -752,6 +760,12 @@ static void x25_asy_setup(struct net_device *dev)
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dev->type = ARPHRD_X25;
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dev->type = ARPHRD_X25;
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dev->tx_queue_len = 10;
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dev->tx_queue_len = 10;
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/* When transmitting data:
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* first this driver removes a pseudo header of 1 byte,
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* then the lapb module prepends an LAPB header of at most 3 bytes.
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*/
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dev->needed_headroom = 3 - 1;
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/* New-style flags. */
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/* New-style flags. */
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dev->flags = IFF_NOARP;
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dev->flags = IFF_NOARP;
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}
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}
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