Fix use after free with hapd->time_adv on interface restart

When an interface is disabled, e.g. due to radar detected,
hapd->time_adv is freed by hostapd_free_hapd_data(), but later
used by ieee802_11_build_ap_params() calling hostapd_eid_time_adv().

Thus hapd->time_adv needs to be cleared as well.

Fixes: 39b97072b2 ("Add support for Time Advertisement")
Signed-off-by: Michael Braun <michael-dev@fami-braun.de>

src/ap/hostapd.c

@@ -414,6 +414,7 @@ void hostapd_free_hapd_data(struct hostapd_data *hapd)
 	}
 
 	wpabuf_free(hapd->time_adv);
+	hapd->time_adv = NULL;
 
 #ifdef CONFIG_INTERWORKING
 	gas_serv_deinit(hapd);