From 17c3feeb0837b6583ed698c6d2430c8d19705dba Mon Sep 17 00:00:00 2001
From: Jon Shallow <supjps-libcoap@jpshallow.com>
Date: Thu, 12 Jun 2025 13:31:19 +0100
Subject: [PATCH] coap_session_mfree: Check for lg_crcv all cleared out if
 failure

Call to coap_cancel_observe_lkd() may cause session->lg_crcv to be cleared
out if transmission failure.
---
 src/coap_session.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/coap_session.c b/src/coap_session.c
index 180e9515..e60271ca 100644
--- a/src/coap_session.c
+++ b/src/coap_session.c
@@ -543,6 +543,9 @@ coap_session_mfree(coap_session_t *session) {
         }
       }
     }
+    /* In case coap_cancel_observe_lkd() failure, which could clear down lg_crcv */
+    if (!session->lg_crcv)
+      break;
     LL_DELETE(session->lg_crcv, lg_crcv);
     coap_block_delete_lg_crcv(session, lg_crcv);
   }