[PATCH] (7/7) Get rid of skb_linearize in ipmr.c

[Stephen Hemminger <shemminger@xxxxxxxx>]

Use explicit may_pull's instead of forcing skb to be linearized.

diff -Nru a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
--- a/net/ipv4/ipmr.c   Wed Jun 25 11:30:41 2003
+++ b/net/ipv4/ipmr.c   Wed Jun 25 11:30:41 2003
@@ -1400,15 +1400,14 @@
 
 int pim_rcv_v1(struct sk_buff * skb)
 {
-       struct igmphdr *pim = (struct igmphdr*)skb->h.raw;
+       struct igmphdr *pim;
        struct iphdr   *encap;
        struct net_device  *reg_dev = NULL;
 
-       if (skb_is_nonlinear(skb)) {
-               if (skb_linearize(skb, GFP_ATOMIC) != 0) 
-                       goto drop;
-               pim = (struct igmphdr*)skb->h.raw;
-       }
+       if (!pskb_may_pull(skb, sizeof(*pim) + sizeof(*encap))) 
+               goto drop;
+
+       pim = (struct igmphdr*)skb->h.raw;
 
         if (!mroute_do_pim ||
            skb->len < sizeof(*pim) + sizeof(*encap) ||
@@ -1465,21 +1464,18 @@
 #ifdef CONFIG_IP_PIMSM_V2
 static int pim_rcv(struct sk_buff * skb)
 {
-       struct pimreghdr *pim = (struct pimreghdr*)skb->h.raw;
+       struct pimreghdr *pim;
        struct iphdr   *encap;
        struct net_device  *reg_dev = NULL;
 
-       if (skb_is_nonlinear(skb)) {
-               if (skb_linearize(skb, GFP_ATOMIC) != 0) 
-                       goto drop;
-               pim = (struct pimreghdr*)skb->h.raw;
-       }
+       if (!pskb_may_pull(skb, sizeof(*pim) + sizeof(*encap))) 
+               goto drop;
 
-        if (skb->len < sizeof(*pim) + sizeof(*encap) ||
-           pim->type != ((PIM_VERSION<<4)|(PIM_REGISTER)) ||
+       pim = (struct pimreghdr*)skb->h.raw;
+        if (pim->type != ((PIM_VERSION<<4)|(PIM_REGISTER)) ||
            (pim->flags&PIM_NULL_REGISTER) ||
-           (ip_compute_csum((void *)pim, sizeof(*pim)) != 0 &&
-            ip_compute_csum((void *)pim, skb->len))) 
+           (ip_compute_csum((void *)pim, sizeof(*pim)) != 0 && 
+            (u16)csum_fold(skb_checksum(skb, 0, skb->len, 0)))) 
                goto drop;
 
        /* check if the inner packet is destined to mcast group */