[ 22/42] mac80211: fix non RCU-safe sta_list manipulation

From: Greg KH
Date: Thu Jun 14 2012 - 19:59:56 EST


3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Arik Nemtsov <arik@xxxxxxxxxx>

commit 794454ce72a298de6f4536ade597bdcc7dcde7c7 upstream.

sta_info_cleanup locks the sta_list using rcu_read_lock however
the delete operation isn't rcu safe. A race between sta_info_cleanup
timer being called and a STA being removed can occur which leads
to a panic while traversing sta_list. Fix this by switching to the
RCU-safe versions.

Reported-by: Eyal Shapira <eyal@xxxxxxxxxx>
Signed-off-by: Arik Nemtsov <arik@xxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/mac80211/sta_info.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -378,7 +378,7 @@ static int sta_info_insert_finish(struct
/* make the station visible */
sta_info_hash_add(local, sta);

- list_add(&sta->list, &local->sta_list);
+ list_add_rcu(&sta->list, &local->sta_list);

set_sta_flag(sta, WLAN_STA_INSERTED);

@@ -688,7 +688,7 @@ int __must_check __sta_info_destroy(stru
if (ret)
return ret;

- list_del(&sta->list);
+ list_del_rcu(&sta->list);

mutex_lock(&local->key_mtx);
for (i = 0; i < NUM_DEFAULT_KEYS; i++)


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