l2tp: fix missing refcount drop in pppol2tp_tunnel_ioctl()

If 'session' is not NULL and is not a PPP pseudo-wire, then we fail to
drop the reference taken by l2tp_session_get().

Fixes: ecd012e45ab5 ("l2tp: filter out non-PPP sessions in pppol2tp_tunnel_ioctl()")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 4 deletions

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index e398797878a9..cf6cca260e7b 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -1201,13 +1201,18 @@ static int pppol2tp_tunnel_ioctl(struct l2tp_tunnel *tunnel,
                                 l2tp_session_get(sock_net(sk), tunnel,
                                                  stats.session_id);
 
-                        if (session && session->pwtype == L2TP_PWTYPE_PPP) {
-                                err = pppol2tp_session_ioctl(session, cmd,
-                                                             arg);
+                        if (!session) {
+                                err = -EBADR;
+                                break;
+                        }
+                        if (session->pwtype != L2TP_PWTYPE_PPP) {
                                 l2tp_session_dec_refcount(session);
-                        } else {
                                 err = -EBADR;
+                                break;
                         }
+
+                        err = pppol2tp_session_ioctl(session, cmd, arg);
+                        l2tp_session_dec_refcount(session);
                         break;
                 }
 #ifdef CONFIG_XFRM