net: 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>

2 files changed, 6 insertions, 4 deletions

diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
index aab73757bc4d..3bd22795c3e2 100644
--- a/include/net/inet_ecn.h
+++ b/include/net/inet_ecn.h
@@ -134,12 +134,14 @@ static inline int INET_ECN_set_ce(struct sk_buff *skb)
 {
         switch (skb->protocol) {
         case cpu_to_be16(ETH_P_IP):
-                if (skb->network_header + sizeof(struct iphdr) <= skb->tail)
+                if (skb_network_header(skb) + sizeof(struct iphdr) <=
+                    skb_tail_pointer(skb))
                         return IP_ECN_set_ce(ip_hdr(skb));
                 break;
 
         case cpu_to_be16(ETH_P_IPV6):
-                if (skb->network_header + sizeof(struct ipv6hdr) <= skb->tail)
+                if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
+                    skb_tail_pointer(skb))
                         return IP6_ECN_set_ce(ipv6_hdr(skb));
                 break;
         }
diff --git a/net/core/dev.c b/net/core/dev.c
index b2e9057be3bf..d4d874a25e45 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1724,7 +1724,7 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
                         skb_reset_mac_header(skb2);
 
                         if (skb_network_header(skb2) < skb2->data ||
-                            skb2->network_header > skb2->tail) {
+                            skb_network_header(skb2) > skb_tail_pointer(skb2)) {
                                 net_crit_ratelimited("protocol %04x is buggy, dev %s\n",
                                                      ntohs(skb2->protocol),
                                                      dev->name);
@@ -3892,7 +3892,7 @@ static void skb_gro_reset_offset(struct sk_buff *skb)
         NAPI_GRO_CB(skb)->frag0 = NULL;
         NAPI_GRO_CB(skb)->frag0_len = 0;
 
-        if (skb->mac_header == skb->tail &&
+        if (skb_mac_header(skb) == skb_tail_pointer(skb) &&
             pinfo->nr_frags &&
             !PageHighMem(skb_frag_page(frag0))) {
                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);