From 89e9bfc4ee859ad2a477f10aa2d5c37377242296 Mon Sep 17 00:00:00 2001
From: Chunho Lee <handera@gmail.com>
Date: Fri, 7 Jul 2017 17:03:14 -0700
Subject: [PATCH] mac80211: Fix null pointer dereference with iTXQ support
Git-commit: 89e9bfc4ee859ad2a477f10aa2d5c37377242296
Patch-mainline: v4.14-rc1
References: FATE#326294

This change adds null pointer check before dereferencing pointer dev on
netif_tx_start_all_queues() when an interface is added.
With iTXQ support, netif_tx_start_all_queues() is always called while
an interface is added. however, the netdev queues are not associated
and dev is null when the interface is either NL80211_IFTYPE_P2P_DEVICE
or NL80211_IFTYPE_NAN.

Signed-off-by: Chunho Lee <ch.lee@newracom.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/mac80211/iface.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 44399322f356..f75029abf728 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -731,7 +731,8 @@ int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
 	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
 	    local->ops->wake_tx_queue) {
 		/* XXX: for AP_VLAN, actually track AP queues */
-		netif_tx_start_all_queues(dev);
+		if (dev)
+			netif_tx_start_all_queues(dev);
 	} else if (dev) {
 		unsigned long flags;
 		int n_acs = IEEE80211_NUM_ACS;
-- 
2.19.2