Fix out-of-bounds read on node coordinates.

src/visualisations.cpp

@@ -15,6 +15,32 @@ static constexpr size_t INTERACTION_LIMIT = 10000;
 
 typedef vector<pair<float, pair<size_t, size_t>>> EntryList;
 
+/**
+ * Normalizer for node positions.
+ *
+ * Since not every neuron in a layer may get a node in the visualisation,
+ * this function maps those neurons back to a node number that does.
+ *
+ * Usage: node / getNodeNormalizer(layer).
+ *
+ * @param layer Layer to compute normalization for
+ * @return Number to divide node numbers by.
+ */
+static inline int getNodeNormalizer(const LayerData& layer) {
+    const auto& shape = layer.shape();
+    switch(shape.size()) {
+        case 2:
+            return 1;
+
+        case 4:
+            return shape[2] * shape[3];
+
+        default:
+            CHECK(false) << "Unsupported shape " << shape.size() << endl;
+            exit(EINVAL);
+    }
+}
+
 fmri::LayerVisualisation *fmri::getVisualisationForLayer(const fmri::LayerData &layer)
 {
     switch (layer.shape().size()) {
@@ -55,22 +81,27 @@ static Animation *getFullyConnectedAnimation(const fmri::LayerData &prevState, c
 
     EntryList result;
     result.reserve(desiredSize);
+    const auto normalizer = getNodeNormalizer(prevState);
     for (auto i : idx) {
-        result.emplace_back(interactions[i], make_pair(i / shape[0], i % shape[0]));
+        result.emplace_back(interactions[i], make_pair(i / shape[0] / normalizer, i % shape[0]));
     }
 
     return new ActivityAnimation(result, prevPositions.data(), curPositions.data(), -10);
 }
 
-static Animation *getDropOutAnimation(const fmri::LayerData &curState,
+static Animation *getDropOutAnimation(const fmri::LayerData &prevState,
+                                      const fmri::LayerData &curState,
                                       const vector<float> &prevPositions,
                                       const vector<float> &curPositions) {
+    const auto sourceNormalize = getNodeNormalizer(prevState);
+    const auto sinkNormalize = getNodeNormalizer(curState);
+
     auto data = curState.data();
     EntryList results;
     results.reserve(curState.numEntries());
     for (auto i : Range(curState.numEntries())) {
         if (data[i] != 0) {
-            results.emplace_back(data[i], make_pair(i, i));
+            results.emplace_back(data[i], make_pair(i / sourceNormalize, i / sinkNormalize));
         }
     }
 
@@ -93,7 +124,7 @@ Animation * fmri::getActivityAnimation(const fmri::LayerData &prevState, const f
                                               prevPositions, curPositions);
 
         case LayerInfo::Type::DropOut:
-            return getDropOutAnimation(curState, prevPositions, curPositions);
+            return getDropOutAnimation(prevState, curState, prevPositions, curPositions);
 
 
         default: