From a50004baffb05ce92656e3db5828933acebfb743 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Tue, 25 Jun 2019 12:56:48 +1000
Subject: [PATCH] Rover: add sanity check when fetching GCS_MAVLink instance

---
 APMrover2/GCS_Rover.h | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/APMrover2/GCS_Rover.h b/APMrover2/GCS_Rover.h
index fe0151c445..abb0f553ba 100644
--- a/APMrover2/GCS_Rover.h
+++ b/APMrover2/GCS_Rover.h
@@ -13,9 +13,21 @@ public:
     uint8_t num_gcs() const override { return ARRAY_SIZE(_chan); };
 
     // return GCS link at offset ofs
-    GCS_MAVLINK_Rover &chan(const uint8_t ofs) override { return _chan[ofs]; };
+    GCS_MAVLINK_Rover &chan(uint8_t ofs) override {
+        if (ofs >= num_gcs()) {
+            AP::internalerror().error(AP_InternalError::error_t::gcs_offset);
+            ofs = 0;
+        }
+        return _chan[ofs];
+    }
     // return GCS link at offset ofs
-    const GCS_MAVLINK_Rover &chan(const uint8_t ofs) const override { return _chan[ofs]; };
+    const GCS_MAVLINK_Rover &chan(uint8_t ofs) const override {
+        if (ofs >= num_gcs()) {
+            AP::internalerror().error(AP_InternalError::error_t::gcs_offset);
+            ofs = 0;
+        }
+        return _chan[ofs];
+    }
 
     uint32_t custom_mode() const override;
     MAV_TYPE frame_type() const override;