RDMA/siw: Fix IPv6 addr_list locking

Walking the address list of an inet6_dev requires
appropriate locking. Since the called function
siw_listen_address() may sleep, we have to use
rtnl_lock() instead of read_lock_bh().

Also introduces sanity checks if we got a device
from in_dev_get() or in6_dev_get().
Reported-by: Bart Van Assche <bvanassche@acm.org>
Fixes: 6c52fdc2 ("rdma/siw: connection management")
Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com>
Link: https://lore.kernel.org/r/20190828130355.22830-1-bmt@zurich.ibm.comSigned-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/siw/siw_cm.c

@@ -1962,6 +1962,10 @@ int siw_create_listen(struct iw_cm_id *id, int backlog)
 		struct sockaddr_in s_laddr, *s_raddr;
 		const struct in_ifaddr *ifa;
 
+		if (!in_dev) {
+			rv = -ENODEV;
+			goto out;
+		}
 		memcpy(&s_laddr, &id->local_addr, sizeof(s_laddr));
 		s_raddr = (struct sockaddr_in *)&id->remote_addr;
 
@@ -1991,22 +1995,27 @@ int siw_create_listen(struct iw_cm_id *id, int backlog)
 		struct sockaddr_in6 *s_laddr = &to_sockaddr_in6(id->local_addr),
 			*s_raddr = &to_sockaddr_in6(id->remote_addr);
 
+		if (!in6_dev) {
+			rv = -ENODEV;
+			goto out;
+		}
 		siw_dbg(id->device,
 			"laddr %pI6:%d, raddr %pI6:%d\n",
 			&s_laddr->sin6_addr, ntohs(s_laddr->sin6_port),
 			&s_raddr->sin6_addr, ntohs(s_raddr->sin6_port));
 
-		read_lock_bh(&in6_dev->lock);
+		rtnl_lock();
 		list_for_each_entry(ifp, &in6_dev->addr_list, if_list) {
-			struct sockaddr_in6 bind_addr;
-
+			if (ifp->flags & (IFA_F_TENTATIVE | IFA_F_DEPRECATED))
+				continue;
 			if (ipv6_addr_any(&s_laddr->sin6_addr) ||
 			    ipv6_addr_equal(&s_laddr->sin6_addr, &ifp->addr)) {
-				bind_addr.sin6_family = AF_INET6;
-				bind_addr.sin6_port = s_laddr->sin6_port;
-				bind_addr.sin6_flowinfo = 0;
-				bind_addr.sin6_addr = ifp->addr;
-				bind_addr.sin6_scope_id = dev->ifindex;
+				struct sockaddr_in6 bind_addr  = {
+					.sin6_family = AF_INET6,
+					.sin6_port = s_laddr->sin6_port,
+					.sin6_flowinfo = 0,
+					.sin6_addr = ifp->addr,
+					.sin6_scope_id = dev->ifindex };
 
 				rv = siw_listen_address(id, backlog,
 						(struct sockaddr *)&bind_addr,
@@ -2015,12 +2024,12 @@ int siw_create_listen(struct iw_cm_id *id, int backlog)
 					listeners++;
 			}
 		}
-		read_unlock_bh(&in6_dev->lock);
-
+		rtnl_unlock();
 		in6_dev_put(in6_dev);
 	} else {
-		return -EAFNOSUPPORT;
+		rv = -EAFNOSUPPORT;
 	}
+out:
 	if (listeners)
 		rv = 0;
 	else if (!rv)