From: Paul Durrant Date: Fri, 7 Oct 2016 08:32:31 +0000 (+0100) Subject: xen-netback: make sure that hashes are not send to unaware frontends X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=912e27e85e070596ed4964ebde29fa9781390f2a;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git xen-netback: make sure that hashes are not send to unaware frontends In the case when a frontend only negotiates a single queue with xen- netback it is possible for a skbuff with a s/w hash to result in a hash extra_info segment being sent to the frontend even when no hash algorithm has been configured. (The ndo_select_queue() entry point makes sure the hash is not set if no algorithm is configured, but this entry point is not called when there is only a single queue). This can result in a frontend that is unable to handle extra_info segments being given such a segment, causing it to crash. This patch fixes the problem by clearing the hash in ndo_start_xmit() instead, which is clearly guaranteed to be called irrespective of the number of queues. Signed-off-by: Paul Durrant Cc: Wei Liu Acked-by: Wei Liu Signed-off-by: David S. Miller --- diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 4af532a67d95..74dc2bf71428 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -149,17 +149,8 @@ static u16 xenvif_select_queue(struct net_device *dev, struct sk_buff *skb, struct xenvif *vif = netdev_priv(dev); unsigned int size = vif->hash.size; - if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) { - u16 index = fallback(dev, skb) % dev->real_num_tx_queues; - - /* Make sure there is no hash information in the socket - * buffer otherwise it would be incorrectly forwarded - * to the frontend. - */ - skb_clear_hash(skb); - - return index; - } + if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) + return fallback(dev, skb) % dev->real_num_tx_queues; xenvif_set_skb_hash(vif, skb); @@ -208,6 +199,13 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) cb = XENVIF_RX_CB(skb); cb->expires = jiffies + vif->drain_timeout; + /* If there is no hash algorithm configured then make sure there + * is no hash information in the socket buffer otherwise it + * would be incorrectly forwarded to the frontend. + */ + if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) + skb_clear_hash(skb); + xenvif_rx_queue_tail(queue, skb); xenvif_kick_thread(queue);