On Mon, 2010-07-26 at 15:52 -0700, Jouni Malinen wrote:
> 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@xxxxx>
Reviewed-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> ---
> net/mac80211/cfg.c | 6 +++---
> net/mac80211/key.c | 13 ++++++-------
> net/mac80211/key.h | 3 ++-
> net/mac80211/sta_info.c | 2 +-
> 4 files changed, 12 insertions(+), 12 deletions(-)
>
> (Note: The reference to key locking simplification is to the commit
> ad0e2b5a00dbec303e4682b403bb6703d11dcdb2 which is not yet in linux-2.6.)
Yes, this is because it's in wireless-next-2.6, the commit ID should
still be stable.
johannes
> --- wireless-testing.orig/net/mac80211/cfg.c 2010-07-26 14:44:01.000000000 -0700
> +++ wireless-testing/net/mac80211/cfg.c 2010-07-26 14:44:43.000000000 -0700
> @@ -158,7 +158,7 @@ static int ieee80211_add_key(struct wiph
> 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 wiph
> 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 wiph
> 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;
> --- wireless-testing.orig/net/mac80211/key.c 2010-07-26 14:43:07.000000000 -0700
> +++ wireless-testing/net/mac80211/key.c 2010-07-26 14:44:43.000000000 -0700
> @@ -323,13 +323,15 @@ static void __ieee80211_key_destroy(stru
> 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_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);
> --- wireless-testing.orig/net/mac80211/key.h 2010-07-26 14:43:07.000000000 -0700
> +++ wireless-testing/net/mac80211/key.h 2010-07-26 14:44:43.000000000 -0700
> @@ -135,7 +135,8 @@ struct ieee80211_key *ieee80211_key_allo
> 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);
> --- wireless-testing.orig/net/mac80211/sta_info.c 2010-07-26 14:43:07.000000000 -0700
> +++ wireless-testing/net/mac80211/sta_info.c 2010-07-26 14:44:43.000000000 -0700
> @@ -647,7 +647,7 @@ static int __must_check __sta_info_destr
> return ret;
>
> if (sta->key) {
> - ieee80211_key_free(sta->key);
> + ieee80211_key_free(local, sta->key);
> WARN_ON(sta->key);
> }
>
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