ipv6: Correct comparisons and calculations using skb->tail and skb-transport_header

This corrects an regression introduced by "net: Use 16bits for *_headers
fields of struct skbuff" when NET_SKBUFF_DATA_USES_OFFSET is not set. In
that case skb->tail will be a pointer whereas skb->transport_header
will be an offset from head. This is corrected by using wrappers that
ensure that comparisons and calculations are always made using pointers.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 194c3cde1536..2b874185ebb2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1649,7 +1649,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
         int optlen, on_link;
         u8 *lladdr;
 
-        optlen = skb->tail - skb->transport_header;
+        optlen = skb_tail_pointer(skb) - skb_transport_header(skb);
         optlen -= sizeof(*msg);
 
         if (optlen < 0) {