l2tp: fix oops in L2TP IP sockets for connect() AF_UNSPEC case
[ Upstream commit c51ce49735c183ef2592db70f918ee698716276b ]
An application may call connect() to disconnect a socket using an
address with family AF_UNSPEC. The L2TP IP sockets were not handling
this case when the socket is not bound and an attempt to connect()
using AF_UNSPEC in such cases would result in an oops. This patch
addresses the problem by protecting the sk_prot->disconnect() call
against trying to unhash the socket before it is bound.
The patch also adds more checks that the sockaddr supplied to bind()
and connect() calls is valid.
RIP: 0010:[<ffffffff82e133b0>] [<ffffffff82e133b0>] inet_unhash+0x50/0xd0
RSP: 0018:ffff88001989be28 EFLAGS: 00010293
Stack:
ffff8800407a8000 0000000000000000 ffff88001989be78 ffffffff82e3a249
ffffffff82e3a050 ffff88001989bec8 ffff88001989be88 ffff8800407a8000
0000000000000010 ffff88001989bec8 ffff88001989bea8 ffffffff82e42639
Call Trace:
[<ffffffff82e3a249>] udp_disconnect+0x1f9/0x290
[<ffffffff82e42639>] inet_dgram_connect+0x29/0x80
[<ffffffff82d012fc>] sys_connect+0x9c/0x100
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 6274f0b..cc8ad7b 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -251,9 +251,16 @@
{
struct inet_sock *inet = inet_sk(sk);
struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
- int ret = -EINVAL;
+ int ret;
int chk_addr_ret;
+ if (!sock_flag(sk, SOCK_ZAPPED))
+ return -EINVAL;
+ if (addr_len < sizeof(struct sockaddr_l2tpip))
+ return -EINVAL;
+ if (addr->l2tp_family != AF_INET)
+ return -EINVAL;
+
ret = -EADDRINUSE;
read_lock_bh(&l2tp_ip_lock);
if (__l2tp_ip_bind_lookup(&init_net, addr->l2tp_addr.s_addr, sk->sk_bound_dev_if, addr->l2tp_conn_id))
@@ -284,6 +291,8 @@
sk_del_node_init(sk);
write_unlock_bh(&l2tp_ip_lock);
ret = 0;
+ sock_reset_flag(sk, SOCK_ZAPPED);
+
out:
release_sock(sk);
@@ -304,13 +313,14 @@
__be32 saddr;
int oif, rc;
- rc = -EINVAL;
- if (addr_len < sizeof(*lsa))
- goto out;
+ if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
+ return -EINVAL;
- rc = -EAFNOSUPPORT;
+ if (addr_len < sizeof(*lsa))
+ return -EINVAL;
+
if (lsa->l2tp_family != AF_INET)
- goto out;
+ return -EAFNOSUPPORT;
lock_sock(sk);
@@ -364,6 +374,14 @@
return rc;
}
+static int l2tp_ip_disconnect(struct sock *sk, int flags)
+{
+ if (sock_flag(sk, SOCK_ZAPPED))
+ return 0;
+
+ return udp_disconnect(sk, flags);
+}
+
static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
int *uaddr_len, int peer)
{
@@ -599,7 +617,7 @@
.close = l2tp_ip_close,
.bind = l2tp_ip_bind,
.connect = l2tp_ip_connect,
- .disconnect = udp_disconnect,
+ .disconnect = l2tp_ip_disconnect,
.ioctl = udp_ioctl,
.destroy = l2tp_ip_destroy_sock,
.setsockopt = ip_setsockopt,