Phonet: Correct header retrieval after pskb_may_pull

Retrieve the header after doing pskb_may_pull since, pskb_may_pull
could change the buffer structure.

This is based on the comment given by Eric Dumazet on Phonet
Pipe controller patch for a similar problem.

Signed-off-by: Kumar Sanghvi <kumar.sanghvi@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index b2a3ae6cad78..15003021f4f0 100644
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -225,12 +225,13 @@ static void pipe_grant_credits(struct sock *sk)
 static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
 {
         struct pep_sock *pn = pep_sk(sk);
-        struct pnpipehdr *hdr = pnp_hdr(skb);
+        struct pnpipehdr *hdr;
         int wake = 0;
 
         if (!pskb_may_pull(skb, sizeof(*hdr) + 4))
                 return -EINVAL;
 
+        hdr = pnp_hdr(skb);
         if (hdr->data[0] != PN_PEP_TYPE_COMMON) {
                 LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP type: %u\n",
                                 (unsigned)hdr->data[0]);