From 71ddd3bd6149544daa24f512e2090d57a7288f09 Mon Sep 17 00:00:00 2001
From: Jose Alamos <jose@alamos.cc>
Date: Thu, 24 Jun 2021 15:03:17 +0200
Subject: [PATCH 1/2] gnrc_lorawan: fix undefined state when PSDU is NULL

---
 sys/include/net/gnrc/lorawan.h                  | 11 +++++++++++
 sys/net/gnrc/netif/lorawan/gnrc_netif_lorawan.c |  4 ++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/sys/include/net/gnrc/lorawan.h b/sys/include/net/gnrc/lorawan.h
index 1feaf57485..d6f7ee38f5 100644
--- a/sys/include/net/gnrc/lorawan.h
+++ b/sys/include/net/gnrc/lorawan.h
@@ -176,6 +176,17 @@ void gnrc_lorawan_radio_rx_timeout_cb(gnrc_lorawan_t *mac);
  */
 void gnrc_lorawan_radio_tx_done_cb(gnrc_lorawan_t *mac);
 
+/**
+ * @brief Indicate the MAC layer reception of a frame went wrong.
+ *
+ * @param[in] mac pointer to the MAC descriptor
+ */
+static inline void gnrc_lorawan_radio_rx_error_cb(gnrc_lorawan_t *mac)
+{
+    /* The failed reception is seen by the MAC layer as an RX timeout */
+    gnrc_lorawan_radio_rx_timeout_cb(mac);
+}
+
 /**
  * @brief Indicate the MAC layer that the timer was fired
  *
diff --git a/sys/net/gnrc/netif/lorawan/gnrc_netif_lorawan.c b/sys/net/gnrc/netif/lorawan/gnrc_netif_lorawan.c
index 51b06f2ac3..34ac42257e 100644
--- a/sys/net/gnrc/netif/lorawan/gnrc_netif_lorawan.c
+++ b/sys/net/gnrc/netif/lorawan/gnrc_netif_lorawan.c
@@ -180,13 +180,13 @@ static void _rx_done(gnrc_lorawan_t *mac)
         DEBUG("_recv_lorawan: cannot allocate pktsnip.\n");
         /* Discard packet on netdev device */
         dev->driver->recv(dev, NULL, bytes_expected, NULL);
-        gnrc_lorawan_radio_rx_done_cb(mac, NULL, 0);
+        gnrc_lorawan_radio_rx_error_cb(mac);
         return;
     }
     nread = dev->driver->recv(dev, pkt->data, bytes_expected, &rx_info);
     if (nread <= 0) {
         gnrc_pktbuf_release(pkt);
-        gnrc_lorawan_radio_rx_done_cb(mac, NULL, 0);
+        gnrc_lorawan_radio_rx_error_cb(mac);
         return;
     }
 

From a90e5e6fc484d319cc8bf8a4990e8640ec5934ae Mon Sep 17 00:00:00 2001
From: Jose Alamos <jose@alamos.cc>
Date: Thu, 24 Jun 2021 15:56:23 +0200
Subject: [PATCH 2/2] gnrc_lorawan: update gnrc_lorawan_radio_rx_done function

---
 sys/include/net/gnrc/lorawan.h                 | 5 +++--
 sys/net/gnrc/link_layer/lorawan/gnrc_lorawan.c | 4 +---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/sys/include/net/gnrc/lorawan.h b/sys/include/net/gnrc/lorawan.h
index d6f7ee38f5..1571b3153c 100644
--- a/sys/include/net/gnrc/lorawan.h
+++ b/sys/include/net/gnrc/lorawan.h
@@ -237,8 +237,9 @@ void gnrc_lorawan_mcps_request(gnrc_lorawan_t *mac,
  *        To be called on radio RX done event.
  *
  * @param[in] mac pointer to the MAC descriptor
- * @param[in] data pointer to the psdu. Pass NULL if the packet was wrong (or
- * allocation failed)
+ * @param[in] data pointer to the psdu. Must not be NULL. Use
+ *            @ref gnrc_lorawan_radio_rx_error_cb instead if the reception was
+ *            not successful.
  * @param[in] size size of the PSDU
  */
 void gnrc_lorawan_radio_rx_done_cb(gnrc_lorawan_t *mac, uint8_t *data,
diff --git a/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan.c b/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan.c
index efeab23dd7..3a3cfa1ff8 100644
--- a/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan.c
+++ b/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan.c
@@ -242,10 +242,8 @@ void gnrc_lorawan_send_pkt(gnrc_lorawan_t *mac, iolist_t *psdu, uint8_t dr)
 void gnrc_lorawan_radio_rx_done_cb(gnrc_lorawan_t *mac, uint8_t *psdu,
                                    size_t size)
 {
+    assert(psdu);
     _sleep_radio(mac);
-    if (psdu == NULL) {
-        return;
-    }
     mac->state = LORAWAN_STATE_IDLE;
     gnrc_lorawan_remove_timer(mac);