netpoll: fix position of network header

Similar to the problem in pktgen, netpoll uses skb_tail_offset()
too, as the code is copied from pktgen.

Also use return values of skb_put() directly, this will simiplify
the code.

Reported-by: Thomas Graf <tgraf@suug.ch>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Daniel Borkmann <dborkmann@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 16 deletions

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 688517c7ff17..03c8ec3edc72 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -676,8 +676,6 @@ static void netpoll_neigh_reply(struct sk_buff *skb, struct netpoll_info *npinfo
 
                 spin_lock_irqsave(&npinfo->rx_lock, flags);
                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
-                        unsigned long tail_offset;
-
                         if (!ipv6_addr_equal(daddr, &np->local_ip.in6))
                                 continue;
 
@@ -691,30 +689,20 @@ static void netpoll_neigh_reply(struct sk_buff *skb, struct netpoll_info *npinfo
                         send_skb->dev = skb->dev;
 
                         skb_reset_network_header(send_skb);
-                        skb_put(send_skb, sizeof(struct ipv6hdr));
-                        hdr = ipv6_hdr(send_skb);
-
+                        hdr = (struct ipv6hdr *) skb_put(send_skb, sizeof(struct ipv6hdr));
                         *(__be32*)hdr = htonl(0x60000000);
-
                         hdr->payload_len = htons(size);
                         hdr->nexthdr = IPPROTO_ICMPV6;
                         hdr->hop_limit = 255;
                         hdr->saddr = *saddr;
                         hdr->daddr = *daddr;
 
-                        tail_offset = skb_tail_offset(skb);
-                        if (tail_offset > 0xffff) {
-                                kfree_skb(send_skb);
-                                continue;
-                        }
-                        skb_set_network_header(send_skb, tail_offset);
-                        skb_put(send_skb, size);
-
-                        icmp6h = (struct icmp6hdr *)skb_transport_header(skb);
+                        icmp6h = (struct icmp6hdr *) skb_put(send_skb, sizeof(struct icmp6hdr));
                         icmp6h->icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
                         icmp6h->icmp6_router = 0;
                         icmp6h->icmp6_solicited = 1;
-                        target = (struct in6_addr *)(skb_transport_header(send_skb) + sizeof(struct icmp6hdr));
+
+                        target = (struct in6_addr *) skb_put(send_skb, sizeof(struct in6_addr));
                         *target = msg->target;
                         icmp6h->icmp6_cksum = csum_ipv6_magic(saddr, daddr, size,
                                                               IPPROTO_ICMPV6,