From e52fed7177f74382f742c27de2cc5314790aebb6 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Sun, 23 Oct 2016 21:32:47 -0700 Subject: [PATCH] netvsc: fix incorrect receive checksum offloading The Hyper-V netvsc driver was looking at the incorrect status bits in the checksum info. It was setting the receive checksum unnecessary flag based on the IP header checksum being correct. The checksum flag is skb is about TCP and UDP checksum status. Because of this bug, any packet received with bad TCP checksum would be passed up the stack and to the application causing data corruption. The problem is reproducible via netcat and netem. This had a side effect of not doing receive checksum offload on IPv6. The driver was also also always doing checksum offload independent of the checksum setting done via ethtool. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- drivers/net/hyperv/netvsc_drv.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 5d6e75a40d38..c71d966d905f 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -607,15 +607,18 @@ static struct sk_buff *netvsc_alloc_recv_skb(struct net_device *net, packet->total_data_buflen); skb->protocol = eth_type_trans(skb, net); - if (csum_info) { - /* We only look at the IP checksum here. - * Should we be dropping the packet if checksum - * failed? How do we deal with other checksums - TCP/UDP? - */ - if (csum_info->receive.ip_checksum_succeeded) + + /* skb is already created with CHECKSUM_NONE */ + skb_checksum_none_assert(skb); + + /* + * In Linux, the IP checksum is always checked. + * Do L4 checksum offload if enabled and present. + */ + if (csum_info && (net->features & NETIF_F_RXCSUM)) { + if (csum_info->receive.tcp_checksum_succeeded || + csum_info->receive.udp_checksum_succeeded) skb->ip_summed = CHECKSUM_UNNECESSARY; - else - skb->ip_summed = CHECKSUM_NONE; } if (vlan_tci & VLAN_TAG_PRESENT) -- 2.20.1