Fix use before null check

src/sn_utils.c

@@ -1348,8 +1348,10 @@ static int re_register_and_purge_supernodes (n2n_sn_t *sss, struct sn_community
         }
 
         // purge long-time-not-seen supernodes
-        purge_expired_nodes(&(comm->edges), sss->sock, &sss->tcp_connections, p_last_re_reg_and_purge,
+        if (comm) {
-                            RE_REG_AND_PURGE_FREQUENCY, LAST_SEEN_SN_INACTIVE);
+            purge_expired_nodes(&(comm->edges), sss->sock, &sss->tcp_connections, p_last_re_reg_and_purge,
+                                RE_REG_AND_PURGE_FREQUENCY, LAST_SEEN_SN_INACTIVE);
+        }
     }
 
     if(comm != NULL) {

src/transform_aes.c

@@ -41,10 +41,9 @@ static int transop_deinit_aes (n2n_trans_op_t *arg) {
 
     transop_aes_t *priv = (transop_aes_t *)arg->priv;
 
-    if(priv->ctx)
-        aes_deinit(priv->ctx);
-
     if(priv)
+        if(priv->ctx)
+            aes_deinit(priv->ctx);
         free(priv);
 
     return 0;

src/transform_cc20.c

@@ -33,10 +33,9 @@ static int transop_deinit_cc20 (n2n_trans_op_t *arg) {
 
     transop_cc20_t *priv = (transop_cc20_t *)arg->priv;
 
-    if(priv->ctx)
-        cc20_deinit(priv->ctx);
-
     if(priv)
+        if(priv->ctx)
+            cc20_deinit(priv->ctx);
         free(priv);
 
     return 0;

src/transform_speck.c

@@ -33,10 +33,9 @@ static int transop_deinit_speck (n2n_trans_op_t *arg) {
 
     transop_speck_t *priv = (transop_speck_t *)arg->priv;
 
-    if(priv->ctx)
-        speck_deinit(priv->ctx);
-
     if(priv)
+        if(priv->ctx)
+            speck_deinit(priv->ctx);
         free(priv);
 
     return 0;

src/transform_tf.c

@@ -41,10 +41,9 @@ static int transop_deinit_tf (n2n_trans_op_t *arg) {
 
     transop_tf_t *priv = (transop_tf_t *)arg->priv;
 
-    if(priv->ctx)
-        tf_deinit(priv->ctx);
-
     if(priv)
+        if(priv->ctx)
+            tf_deinit(priv->ctx);
         free(priv);
 
     return 0;