We have freed the channel there is no subscriber associated anymore

FIXME: Introduce refcounting on the subscriber record. This looks like
a genuine memory leak to me.
diff --git a/src/chan_alloc.c b/src/chan_alloc.c
index d76c929..2520ce5 100644
--- a/src/chan_alloc.c
+++ b/src/chan_alloc.c
@@ -185,6 +185,7 @@
 void lchan_free(struct gsm_lchan *lchan)
 {
 	lchan->type = GSM_LCHAN_NONE;
+	lchan->subscr = 0;
 
 	/* stop the timer */
 	del_timer(&lchan->release_timer);