4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Guillaume Nault <g.nault@xxxxxxxxxxxx> [ Upstream commit 5903f594935a3841137c86b9d5b75143a5b7121c ] When pppol2tp_session_ioctl() is called by pppol2tp_tunnel_ioctl(), the session may be unconnected. That is, it was created by pppol2tp_session_create() and hasn't been connected with pppol2tp_connect(). In this case, ps->sock is NULL, so we need to check for this case in order to avoid dereferencing a NULL pointer. Fixes: 309795f4bec2 ("l2tp: Add netlink control API for L2TP") Signed-off-by: Guillaume Nault <g.nault@xxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/l2tp/l2tp_ppp.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -1015,6 +1015,9 @@ static int pppol2tp_session_ioctl(struct session->name, cmd, arg); sk = ps->sock; + if (!sk) + return -EBADR; + sock_hold(sk); switch (cmd) {