From: Sabrina Dubroca <sd@queasysnail.net>
Date: Tue, 10 Apr 2018 16:28:55 +0200
Subject: tun: set the flags before registering the netdevice
Patch-mainline: v4.17-rc1
Git-commit: 9fffc5c6dd7dafb2e021dbbe9a30be2566a6949a
References: bsc#1109837

Otherwise, register_netdevice advertises the creation of the device with
the default flags, instead of what the user requested.

Reported-by: Thomas Haller <thaller@redhat.com>
Fixes: 1ec010e70593 ("tun: export flags, uid, gid, queue information over netlink")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/tun.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2561,6 +2561,9 @@ static int tun_set_iff(struct net *net,
 			 */
 			return 0;
 		}
+
+		tun->flags = (tun->flags & ~TUN_FEATURES) |
+			      (ifr->ifr_flags & TUN_FEATURES);
 	}
 	else {
 		char *name;
@@ -2639,6 +2642,9 @@ static int tun_set_iff(struct net *net,
 				     ~(NETIF_F_HW_VLAN_CTAG_TX |
 				       NETIF_F_HW_VLAN_STAG_TX);
 
+		tun->flags = (tun->flags & ~TUN_FEATURES) |
+			      (ifr->ifr_flags & TUN_FEATURES);
+
 		INIT_LIST_HEAD(&tun->disabled);
 		err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI);
 		if (err < 0)
@@ -2653,9 +2659,6 @@ static int tun_set_iff(struct net *net,
 
 	tun_debug(KERN_INFO, tun, "tun_set_iff\n");
 
-	tun->flags = (tun->flags & ~TUN_FEATURES) |
-		(ifr->ifr_flags & TUN_FEATURES);
-
 	/* Make sure persistent devices do not get stuck in
 	 * xoff state.
 	 */