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mac80211_hwsim: fix locking when iterating radios during ns exit 

The cleanup of radios during namespace exit has recently been reworked
to directly delete a radio while temporarily releasing the spinlock,
fixing a race condition between the work-queue execution and namespace
exits. However, the temporary unlock allows unsafe modifications on the
iterated list, resulting in a potential crash when continuing the
iteration of additional radios.

Move radios about to destroy to a temporary list, and clean that up
after releasing the spinlock once iteration is complete.

Fixes: 8cfd36a0b5 ("mac80211_hwsim: fix use-after-free bug in hwsim_exit_net")
Signed-off-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Martin Willi 2018-09-25 09:41:13 +02:00 committed by Johannes Berg
parent 30fe6d50eb
commit 628980e5c8
1 changed files with 7 additions and 4 deletions
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11
drivers/net/wireless/mac80211_hwsim.c
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@ -3646,6 +3646,7 @@ static __net_init int hwsim_init_net(struct net *net)
static void __net_exit hwsim_exit_net(struct net *net)
{
struct mac80211_hwsim_data *data, *tmp;
LIST_HEAD(list);
spin_lock_bh(&hwsim_radio_lock);
list_for_each_entry_safe(data, tmp, &hwsim_radios, list) {
@ -3656,17 +3657,19 @@ static void __net_exit hwsim_exit_net(struct net *net)
if (data->netgroup == hwsim_net_get_netgroup(&init_net))
continue;
list_del(&data->list);
list_move(&data->list, &list);
rhashtable_remove_fast(&hwsim_radios_rht, &data->rht,
hwsim_rht_params);
hwsim_radios_generation++;
spin_unlock_bh(&hwsim_radio_lock);
}
spin_unlock_bh(&hwsim_radio_lock);
list_for_each_entry_safe(data, tmp, &list, list) {
list_del(&data->list);
mac80211_hwsim_del_radio(data,
wiphy_name(data->hw->wiphy),
NULL);
spin_lock_bh(&hwsim_radio_lock);
}
spin_unlock_bh(&hwsim_radio_lock);
ida_simple_remove(&hwsim_netgroup_ida, hwsim_net_get_netgroup(net));
}