netdev - [PATCH 3/4] PPPoE: memory leak when socket is release()d before PPPIOCGCHAN has been called on it

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Date:	Sun, 11 Mar 2007 05:41:11 +0100
From:	Florian Zumbiehl <florz@...rz.de>
To:	mostrows@...thlink.net, netdev@...r.kernel.org
Subject: [PATCH 3/4] PPPoE: memory leak when socket is release()d before PPPIOCGCHAN has been called on it

Hi,

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 ...

Florian

---------------------------------------------------------------------------
diff --git a/drivers/net/pppox.c b/drivers/net/pppox.c
index 9315046..3f8115d 100644
--- a/drivers/net/pppox.c
+++ b/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;
 	}
-
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