[PATCH 3.16 352/366] ppp: Fix null pointer dereference on registration failure

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <b...@decadent.org.uk>

register_netdevice() will call the device's ndo_uninit operation if
registration fails after it calls the ndo_init operation.  However
ppp_dev_uninit() uses ppp->ppp_net which is currently not set until
after register_netdevice() returns.

This was fixed upstream as part of commit 6d934c70db6e "ppp: add
rtnetlink device creation support".

Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -2732,6 +2732,7 @@ static struct ppp *ppp_create_interface(
 
        ppp = netdev_priv(dev);
        ppp->dev = dev;
+       ppp->ppp_net = net;
        ppp->mru = PPP_MRU;
        init_ppp_file(&ppp->file, INTERFACE);
        ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
@@ -2801,8 +2802,6 @@ static struct ppp *ppp_create_interface(
                goto out2;
        }
 
-       ppp->ppp_net = net;
-
        atomic_inc(&ppp_unit_count);
        mutex_unlock(&pn->all_ppp_mutex);
        rtnl_unlock();