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

Ben Hutchings
2018-10-14T23:11:51Z

From: Ben Hutchings <ben@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 <ben@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();