From f32cd16f77f85c290fd548c0d20d8e2ff16a0659 Mon Sep 17 00:00:00 2001
From: Pavel Kirienko <pavel.kirienko@gmail.com>
Date: Sat, 5 Apr 2014 17:14:55 +0400
Subject: [PATCH] Extra runtime check in CanIOManager queue

---
 libuavcan/src/transport/uc_can_io.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libuavcan/src/transport/uc_can_io.cpp b/libuavcan/src/transport/uc_can_io.cpp
index 20fe36bf66..e3a45a4ef5 100644
--- a/libuavcan/src/transport/uc_can_io.cpp
+++ b/libuavcan/src/transport/uc_can_io.cpp
@@ -136,6 +136,11 @@ void CanTxQueue::push(const CanFrame& frame, MonotonicTime tx_deadline, Qos qos,
 
         // Find a frame with lowest QoS
         Entry* p = queue_.get();
+        if (p == NULL)
+        {
+            UAVCAN_TRACE("CanTxQueue", "Push rejected: Nothing to replace");
+            return;
+        }
         Entry* lowestqos = p;
         while (p)
         {