[PPPOE]: memory leak when socket is release()d before PPPIOCGCHAN has been called on it

below you find a patch that fixes a memory leak when a PPPoE socket is
release()d after it has been connect()ed, but before the PPPIOCGCHAN ioctl
ever has been called on it.

This is somewhat of a security problem, too, since PPPoE sockets can be
created by any user, so any user can easily allocate all the machine's
RAM to non-swappable address space and thus DoS the system.

Is there any specific reason for PPPoE sockets being available to any
unprivileged process, BTW? After all, you need a packet socket for the
discovery stage anyway, so it's unlikely that any unprivileged process
will ever need to create a PPPoE socket, no? Allocating all session IDs
for a known AC is a kind of DoS, too, after all - with Juniper ERXes,
this is really easy, actually, since they don't ever assign session ids
above 8000 ...
Signed-off-by: NFlorian Zumbiehl <florz@florz.de>
Acked-by: NMichal Ostrowski <mostrows@earthlink.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/pppox.c

@@ -58,7 +58,7 @@ void pppox_unbind_sock(struct sock *sk)
 {
 	/* Clear connection to ppp device, if attached. */
 
-	if (sk->sk_state & (PPPOX_BOUND | PPPOX_ZOMBIE)) {
+	if (sk->sk_state & (PPPOX_BOUND | PPPOX_CONNECTED | PPPOX_ZOMBIE)) {
 		ppp_unregister_channel(&pppox_sk(sk)->chan);
 		sk->sk_state = PPPOX_DEAD;
 	}