[PATCH 4.4 17/17] phonet/pep: refuse to enable an unbound pipe

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Rémi Denis-Courmont <remi@remlab.net>

commit 75a2f31520095600f650597c0ac41f48b5ba0068 upstream.

This ioctl() implicitly assumed that the socket was already bound to
a valid local socket name, i.e. Phonet object. If the socket was not
bound, two separate problems would occur:

1) We'd send an pipe enablement request with an invalid source object.
2) Later socket calls could BUG on the socket unexpectedly being
   connected yet not bound to a valid object.

Reported-by: syzbot+2dc91e7fc3dea88b1e8a@syzkaller.appspotmail.com
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/phonet/pep.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -956,6 +956,8 @@ static int pep_ioctl(struct sock *sk, in
 			ret =  -EBUSY;
 		else if (sk->sk_state == TCP_ESTABLISHED)
 			ret = -EISCONN;
+		else if (!pn->pn_sk.sobject)
+			ret = -EADDRNOTAVAIL;
 		else
 			ret = pep_sock_enable(sk, NULL, 0);
 		release_sock(sk);