quoted

quoted

On 25.03.13 at 15:23, David Vrabel [off-list ref] wrote:

On 25/03/13 11:08, Wei Liu wrote:

quoted

The maximum packet including ethernet header that can be handled by netfront 

/

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netback wire format is 65535. Reduce gso_max_size accordingly.

Drop skb and print warning when skb->len > 65535. This can 1) save the effort
to send malformed packet to netback, 2) help spotting misconfiguration of
netfront in the future.

[...]

quoted

--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c

@@ -547,6 +547,18 @@ static int xennet_start_xmit(struct sk_buff *skb, struct 

net_device *dev)

quoted

 	unsigned int len = skb_headlen(skb);
 	unsigned long flags;
 
+	/* Wire format of xen_netif_tx_request only supports skb->len
+	 * < 64K, because size field in xen_netif_tx_request is
+	 * uint16_t. If skb->len is too big, drop it and alert user about
+	 * misconfiguration.
+	 */
+	if (unlikely(skb->len >= (uint16_t)(~0))) {

Suggest a #define for this maximum added to include/xen/interface/io/netif.h

I don't see a point in doing so. If you want the connection to be
explicit, just use typeof() here instead of uint16_t.

Jan