Re: [PATCH 2/6] xen-netfront: reduce gso_max_size to account for ethernet header
From: Sergei Shtylyov <hidden>
Date: 2013-03-25 15:51:43
Hello. On 25-03-2013 15:08, Wei Liu wrote:
The maximum packet including ethernet header that can be handled by netfront / 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.
Signed-off-by: Wei Liu <redacted> --- drivers/net/xen-netfront.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 5527663..3ae9dc1 100644 --- 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) 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))) {
Such types as 'uint16_t' are intended for userland -- use 'u16' instead.
Better still, just use 0xffffu.
WBR, Sergei