PPPOE: fix memory leak (local DoS) (CVE-2007-2525)

This patch 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: Florian Zumbiehl <florz@florz.de>
Signed-off-by: Adrian Bunk <bunk@kernel.org>

diff --git a/drivers/net/pppox.c b/drivers/net/pppox.c
index 9315046b3f5509eebea0b0207f9b36a4a4326c89..3f8115db4d54b2e54fab90efbf376baad483f6a9 100644 (file)
--- 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;
        }