Phonet: Correct header retrieval after pskb_may_pull

[ Upstream commit a91e7d471e2e384035b9746ea707ccdcd353f5dd ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index b6356f3832f6e69cdc3fc7c2a076fab9f22efcd1..c66c3481f77516a1db0f3b4d824765999630c7a3 100644 (file)
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -224,12 +224,13 @@ 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]);