mac80211: Fix key freeing to handle unlinked keys

Key locking simplification removed key->sdata != NULL verification from
ieee80211_key_free(). While that is fine for most use cases, there is one
path where this function can be called with an unlinked key (i.e.,
key->sdata == NULL && key->local == NULL). This results in a NULL pointer
dereference with the current implementation. This is known to happen at
least with FT protocol when wpa_supplicant tries to configure the key
before association.

Avoid the issue by passing in the local pointer to
ieee80211_key_free(). In addition, do not clear the key from hw_accel
or debugfs if it has not yet been added. At least the hw_accel one could
trigger another NULL pointer dereference.

Signed-off-by: Jouni Malinen <j@w1.fi>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

4 files changed, 12 insertions, 12 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index b769567949be..dab6b8efe5fa 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -158,7 +158,7 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
         if (mac_addr) {
                 sta = sta_info_get_bss(sdata, mac_addr);
                 if (!sta) {
-                        ieee80211_key_free(key);
+                        ieee80211_key_free(sdata->local, key);
                         err = -ENOENT;
                         goto out_unlock;
                 }
@@ -192,7 +192,7 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
                         goto out_unlock;
 
                 if (sta->key) {
-                        ieee80211_key_free(sta->key);
+                        ieee80211_key_free(sdata->local, sta->key);
                         WARN_ON(sta->key);
                         ret = 0;
                 }
@@ -205,7 +205,7 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
                 goto out_unlock;
         }
 
-        ieee80211_key_free(sdata->keys[key_idx]);
+        ieee80211_key_free(sdata->local, sdata->keys[key_idx]);
         WARN_ON(sdata->keys[key_idx]);
 
         ret = 0;
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 50d1cff23d8e..1b9d87ed143a 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -323,13 +323,15 @@ static void __ieee80211_key_destroy(struct ieee80211_key *key)
         if (!key)
                 return;
 
-        ieee80211_key_disable_hw_accel(key);
+        if (key->local)
+                ieee80211_key_disable_hw_accel(key);
 
         if (key->conf.alg == ALG_CCMP)
                 ieee80211_aes_key_free(key->u.ccmp.tfm);
         if (key->conf.alg == ALG_AES_CMAC)
                 ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
-        ieee80211_debugfs_key_remove(key);
+        if (key->local)
+                ieee80211_debugfs_key_remove(key);
 
         kfree(key);
 }
@@ -410,15 +412,12 @@ static void __ieee80211_key_free(struct ieee80211_key *key)
         __ieee80211_key_destroy(key);
 }
 
-void ieee80211_key_free(struct ieee80211_key *key)
+void ieee80211_key_free(struct ieee80211_local *local,
+                        struct ieee80211_key *key)
 {
-        struct ieee80211_local *local;
-
         if (!key)
                 return;
 
-        local = key->sdata->local;
-
         mutex_lock(&local->key_mtx);
         __ieee80211_key_free(key);
         mutex_unlock(&local->key_mtx);
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index a3849fa3fce8..b665bbb7a471 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -135,7 +135,8 @@ struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
 void ieee80211_key_link(struct ieee80211_key *key,
                         struct ieee80211_sub_if_data *sdata,
                         struct sta_info *sta);
-void ieee80211_key_free(struct ieee80211_key *key);
+void ieee80211_key_free(struct ieee80211_local *local,
+                        struct ieee80211_key *key);
 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx);
 void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
                                     int idx);
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 67656cbf2b15..6d86f0c1ad04 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -647,7 +647,7 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
                 return ret;
 
         if (sta->key) {
-                ieee80211_key_free(sta->key);
+                ieee80211_key_free(local, sta->key);
                 WARN_ON(sta->key);
         }