From 4c8a9d4bfaf7dbc7d2168494904d79d22cc01db7 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 24 May 2013 01:06:09 +0200 Subject: [PATCH] mac80211: close AP_VLAN interfaces before unregistering all Since Eric's commit efe117ab8 ("Speedup ieee80211_remove_interfaces") there's a bug in mac80211 when it unregisters with AP_VLAN interfaces up. If the AP_VLAN interface was registered after the AP it belongs to (which is the typical case) and then we get into this code path, unregister_netdevice_many() will crash because it isn't prepared to deal with interfaces being closed in the middle of it. Exactly this happens though, because we iterate the list, find the AP master this AP_VLAN belongs to and dev_close() the dependent VLANs. After this, unregister_netdevice_many() won't pick up the fact that the AP_VLAN is already down and will do it again, causing a crash. Cc: stable@vger.kernel.org [2.6.33+] Cc: Eric Dumazet Signed-off-by: Johannes Berg --- net/mac80211/iface.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index 00e2238355f0..ceef64426a8d 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -1703,6 +1703,15 @@ void ieee80211_remove_interfaces(struct ieee80211_local *local) ASSERT_RTNL(); + /* + * Close all AP_VLAN interfaces first, as otherwise they + * might be closed while the AP interface they belong to + * is closed, causing unregister_netdevice_many() to crash. + */ + list_for_each_entry(sdata, &local->interfaces, list) + if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) + dev_close(sdata->dev); + mutex_lock(&local->iflist_mtx); list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) { list_del(&sdata->list); -- 2.20.1