commit f0ff5817d0647bdecd1ec99488db9378e304cf83
Author: sauwming <ming@teluu.com>
Date:   Mon May 17 09:56:27 2021 +0800

    Fix double free of stun session (#2709)

--- a/pjnath/include/pjnath/stun_session.h
+++ b/pjnath/include/pjnath/stun_session.h
@@ -341,6 +341,7 @@ struct pj_stun_tx_data
     pj_pool_t		*pool;		/**< Pool.			    */
     pj_stun_session	*sess;		/**< The STUN session.		    */
     pj_stun_msg		*msg;		/**< The STUN message.		    */
+    pj_bool_t		 is_destroying; /**< Is destroying?		    */
 
     void		*token;		/**< The token.			    */
 
--- a/pjnath/src/pjnath/stun_session.c
+++ b/pjnath/src/pjnath/stun_session.c
@@ -167,16 +167,27 @@ static void tdata_on_destroy(void *arg)
 {
     pj_stun_tx_data *tdata = (pj_stun_tx_data*)arg;
 
+    if (tdata->grp_lock) {
+	pj_grp_lock_dec_ref(tdata->sess->grp_lock);
+    }
+
     pj_pool_safe_release(&tdata->pool);
 }
 
 static void destroy_tdata(pj_stun_tx_data *tdata, pj_bool_t force)
 {
-    TRACE_((THIS_FILE, "tdata %p destroy request, force=%d, tsx=%p", tdata,
-	    force, tdata->client_tsx));
+    TRACE_((THIS_FILE,
+	    "tdata %p destroy request, force=%d, tsx=%p, destroying=%d",
+	    tdata, force, tdata->client_tsx, tdata->is_destroying));
+
+    /* Just return if destroy has been requested before */
+    if (tdata->is_destroying)
+	return;
 
     /* STUN session may have been destroyed, except when tdata is cached. */
 
+    tdata->is_destroying = PJ_TRUE;
+
     if (tdata->res_timer.id != PJ_FALSE) {
 	pj_timer_heap_cancel_if_active(tdata->sess->cfg->timer_heap,
 				       &tdata->res_timer, PJ_FALSE);
@@ -189,7 +200,6 @@ static void destroy_tdata(pj_stun_tx_dat
 	    pj_stun_client_tsx_set_data(tdata->client_tsx, NULL);
 	}
 	if (tdata->grp_lock) {
-	    pj_grp_lock_dec_ref(tdata->sess->grp_lock);
 	    pj_grp_lock_dec_ref(tdata->grp_lock);
 	} else {
 	    tdata_on_destroy(tdata);
@@ -200,11 +210,11 @@ static void destroy_tdata(pj_stun_tx_dat
 	    /* "Probably" this is to absorb retransmission */
 	    pj_time_val delay = {0, 300};
 	    pj_stun_client_tsx_schedule_destroy(tdata->client_tsx, &delay);
+	    tdata->is_destroying = PJ_FALSE;
 
 	} else {
 	    pj_list_erase(tdata);
 	    if (tdata->grp_lock) {
-		pj_grp_lock_dec_ref(tdata->sess->grp_lock);
 		pj_grp_lock_dec_ref(tdata->grp_lock);
 	    } else {
 		tdata_on_destroy(tdata);
@@ -238,7 +248,7 @@ static void on_cache_timeout(pj_timer_he
     sess = tdata->sess;
 
     pj_grp_lock_acquire(sess->grp_lock);
-    if (sess->is_destroying) {
+    if (sess->is_destroying || tdata->is_destroying) {
 	pj_grp_lock_release(sess->grp_lock);
 	return;
     }