From 8b305780ed0c49a49c6bd58a4372fd6b22a5a71e Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 20 Mar 2013 22:25:17 +0100 Subject: [PATCH] mac80211: fix virtual monitor interface locking The virtual monitor interface has a locking issue, it calls into the channel context code with the iflist mutex held which isn't allowed since it is usually acquired the other way around. The mutex is still required for the interface iteration, but need not be held across the channel calls. Signed-off-by: Johannes Berg --- net/mac80211/iface.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index baaa8608e52d..3bfe2612c8c2 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -349,21 +349,19 @@ static void ieee80211_set_default_queues(struct ieee80211_sub_if_data *sdata) static int ieee80211_add_virtual_monitor(struct ieee80211_local *local) { struct ieee80211_sub_if_data *sdata; - int ret = 0; + int ret; if (!(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF)) return 0; - mutex_lock(&local->iflist_mtx); + ASSERT_RTNL(); if (local->monitor_sdata) - goto out_unlock; + return 0; sdata = kzalloc(sizeof(*sdata) + local->hw.vif_data_size, GFP_KERNEL); - if (!sdata) { - ret = -ENOMEM; - goto out_unlock; - } + if (!sdata) + return -ENOMEM; /* set up data */ sdata->local = local; @@ -377,13 +375,13 @@ static int ieee80211_add_virtual_monitor(struct ieee80211_local *local) if (WARN_ON(ret)) { /* ok .. stupid driver, it asked for this! */ kfree(sdata); - goto out_unlock; + return ret; } ret = ieee80211_check_queues(sdata); if (ret) { kfree(sdata); - goto out_unlock; + return ret; } ret = ieee80211_vif_use_channel(sdata, &local->monitor_chandef, @@ -391,13 +389,14 @@ static int ieee80211_add_virtual_monitor(struct ieee80211_local *local) if (ret) { drv_remove_interface(local, sdata); kfree(sdata); - goto out_unlock; + return ret; } + mutex_lock(&local->iflist_mtx); rcu_assign_pointer(local->monitor_sdata, sdata); - out_unlock: mutex_unlock(&local->iflist_mtx); - return ret; + + return 0; } static void ieee80211_del_virtual_monitor(struct ieee80211_local *local) @@ -407,14 +406,20 @@ static void ieee80211_del_virtual_monitor(struct ieee80211_local *local) if (!(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF)) return; + ASSERT_RTNL(); + mutex_lock(&local->iflist_mtx); sdata = rcu_dereference_protected(local->monitor_sdata, lockdep_is_held(&local->iflist_mtx)); - if (!sdata) - goto out_unlock; + if (!sdata) { + mutex_unlock(&local->iflist_mtx); + return; + } rcu_assign_pointer(local->monitor_sdata, NULL); + mutex_unlock(&local->iflist_mtx); + synchronize_net(); ieee80211_vif_release_channel(sdata); @@ -422,8 +427,6 @@ static void ieee80211_del_virtual_monitor(struct ieee80211_local *local) drv_remove_interface(local, sdata); kfree(sdata); - out_unlock: - mutex_unlock(&local->iflist_mtx); } /* -- 2.20.1