wifi: cfg80211: Fix use after free for wext

Key information in wext.connect is not reset on (re)connect and can hold
data from a previous connection.

Reset key data to avoid that drivers or mac80211 incorrectly detect a
WEP connection request and access the freed or already reused memory.

Additionally optimize cfg80211_sme_connect() and avoid an useless
schedule of conn_work.

Fixes: fffd0934b939 ("cfg80211: rework key operation")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230124141856.356646-1-alexander@wetzel-home.de
Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index 123248b..0cc841c 100644 (file)
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -285,6 +285,15 @@ void cfg80211_conn_work(struct work_struct *work)
        wiphy_unlock(&rdev->wiphy);
 }
 
+static void cfg80211_step_auth_next(struct cfg80211_conn *conn,
+                                   struct cfg80211_bss *bss)
+{
+       memcpy(conn->bssid, bss->bssid, ETH_ALEN);
+       conn->params.bssid = conn->bssid;
+       conn->params.channel = bss->channel;
+       conn->state = CFG80211_CONN_AUTHENTICATE_NEXT;
+}
+
 /* Returned bss is reference counted and must be cleaned up appropriately. */
 static struct cfg80211_bss *cfg80211_get_conn_bss(struct wireless_dev *wdev)
 {
@@ -302,10 +311,7 @@ static struct cfg80211_bss *cfg80211_get_conn_bss(struct wireless_dev *wdev)
        if (!bss)
                return NULL;
 
-       memcpy(wdev->conn->bssid, bss->bssid, ETH_ALEN);
-       wdev->conn->params.bssid = wdev->conn->bssid;
-       wdev->conn->params.channel = bss->channel;
-       wdev->conn->state = CFG80211_CONN_AUTHENTICATE_NEXT;
+       cfg80211_step_auth_next(wdev->conn, bss);
        schedule_work(&rdev->conn_work);
 
        return bss;
@@ -597,7 +603,12 @@ static int cfg80211_sme_connect(struct wireless_dev *wdev,
        wdev->conn->params.ssid_len = wdev->u.client.ssid_len;
 
        /* see if we have the bss already */
-       bss = cfg80211_get_conn_bss(wdev);
+       bss = cfg80211_get_bss(wdev->wiphy, wdev->conn->params.channel,
+                              wdev->conn->params.bssid,
+                              wdev->conn->params.ssid,
+                              wdev->conn->params.ssid_len,
+                              wdev->conn_bss_type,
+                              IEEE80211_PRIVACY(wdev->conn->params.privacy));
 
        if (prev_bssid) {
                memcpy(wdev->conn->prev_bssid, prev_bssid, ETH_ALEN);
@@ -608,6 +619,7 @@ static int cfg80211_sme_connect(struct wireless_dev *wdev,
        if (bss) {
                enum nl80211_timeout_reason treason;
 
+               cfg80211_step_auth_next(wdev->conn, bss);
                err = cfg80211_conn_do_work(wdev, &treason);
                cfg80211_put_bss(wdev->wiphy, bss);
        } else {
@@ -1464,6 +1476,15 @@ int cfg80211_connect(struct cfg80211_registered_device *rdev,
        } else {
                if (WARN_ON(connkeys))
                        return -EINVAL;
+
+               /* connect can point to wdev->wext.connect which
+                * can hold key data from a previous connection
+                */
+               connect->key = NULL;
+               connect->key_len = 0;
+               connect->key_idx = 0;
+               connect->crypto.cipher_group = 0;
+               connect->crypto.n_ciphers_pairwise = 0;
        }
 
        wdev->connect_keys = connkeys;