[PATCH 3.16 144/366] l2tp: filter out non-PPP sessions in pppol2tp_tunnel_ioctl()

[Ben Hutchings]

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

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

From: Guillaume Nault <g.nault@xxxxxxxxxxxx>

commit ecd012e45ab5fd76ed57546865897ce35920f56b upstream.

pppol2tp_tunnel_ioctl() can act on an L2TPv3 tunnel, in which case
'session' may be an Ethernet pseudo-wire.

However, pppol2tp_session_ioctl() expects a PPP pseudo-wire, as it
assumes l2tp_session_priv() points to a pppol2tp_session structure. For
an Ethernet pseudo-wire l2tp_session_priv() points to an l2tp_eth_sess
structure instead, making pppol2tp_session_ioctl() access invalid
memory.

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault <g.nault@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/l2tp/l2tp_ppp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -1231,7 +1231,7 @@ static int pppol2tp_tunnel_ioctl(struct
 				l2tp_session_get(sock_net(sk), tunnel,
 						 stats.session_id, true);
 
-			if (session) {
+			if (session && session->pwtype == L2TP_PWTYPE_PPP) {
 				err = pppol2tp_session_ioctl(session, cmd,
 							     arg);
 				if (session->deref)