Prevent installation of an all-zero TK

Properly track whether a PTK has already been installed to the driver
and the TK part cleared from memory. This prevents an attacker from
trying to trick the client into installing an all-zero TK.

This fixes the earlier fix in commit
ad00d64e7d ('Fix TK configuration to the
driver in EAPOL-Key 3/4 retry case') which did not take into account
possibility of an extra message 1/4 showing up between retries of
message 3/4.

Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>

src/common/wpa_common.h

@@ -219,6 +219,7 @@ struct wpa_ptk {
 	size_t kck_len;
 	size_t kek_len;
 	size_t tk_len;
+	int installed; /* 1 if key has already been installed to driver */
 };
 
 struct wpa_gtk {