dnn: Fix dangling pointers returned by GetLayerNames

Dockerfile.opencv-openvino

@@ -5,10 +5,11 @@ LABEL maintainer="hybridgroup"
 ENV DEBIAN_FRONTEND=noninteractive
 USER root
 RUN apt-get update && apt-get install -y --no-install-recommends \
-            git build-essential cmake pkg-config unzip libgtk2.0-dev \
+            git build-essential cmake pkg-config unzip libgtk2.0-dev libgtk-3-0 \
             wget curl ca-certificates libcurl4-openssl-dev libssl-dev \
             libavcodec-dev libavformat-dev libswscale-dev libtbb2 libtbb-dev \
-            libjpeg-dev libpng-dev libtiff-dev libdc1394-22-dev && \
+            libjpeg-dev libpng-dev libtiff-dev libdc1394-22-dev libcanberra-gtk-module \
+            libcanberra-gtk3-module && \
             rm -rf /var/lib/apt/lists/*
 
 ARG OPENCV_VERSION="4.6.0"
@@ -39,7 +40,6 @@ RUN curl -Lo opencv.zip https://github.com/opencv/opencv/archive/${OPENCV_VERSIO
             -D BUILD_opencv_python3=NO \
             -D WITH_TBB=ON \
             -D WITH_OPENVINO=1 \
-            -D ENABLE_FAST_MATH=1 \
             -D OPENCV_GENERATE_PKGCONFIG=ON .. && \
     make -j $(nproc --all) && \
     make preinstall && make install && ldconfig && \

dnn.cpp

@@ -111,15 +111,38 @@ void Net_GetUnconnectedOutLayers(Net net, IntVector* res) {
 
 void Net_GetLayerNames(Net net, CStrings* names) {
     std::vector< cv::String > cstrs(net->getLayerNames());
-    const char **strs = new const char*[cstrs.size()];
 
-    for (size_t i = 0; i < cstrs.size(); ++i) {
-        strs[i] = cstrs[i].c_str();
+    size_t totalStrLen = 0;
+    for (cv::String str : cstrs) {
+        totalStrLen += str.size();
+    }
+
+    // Compute 1D buffer size required to store
+    // 2D array of null-terminated strings
+    size_t numStrings = cstrs.size();
+    size_t bufferLen = numStrings * sizeof(char*) + (totalStrLen + numStrings) * sizeof(char);
+
+    const char **strs = (const char**)new char[bufferLen];
+    memset(strs, 0, bufferLen);
+
+    char* it = (char*)(strs + cstrs.size());
+    const char* end = (char*)(strs) + bufferLen;
+
+    for (size_t i = 0; i < numStrings; ++i, ++it) {
+        strs[i] = it;
+        size_t strlen = cstrs[i].size();
+
+        // Avoid buffer overrun
+        if(end < it + strlen + 1) {
+            break;
+        }
+
+        memcpy(it, cstrs[i].c_str(), strlen);
+        it += strlen;
     }
 
     names->length = cstrs.size();
     names->strs = strs;
-    return;
 }
 
 Mat Net_BlobFromImage(Mat image, double scalefactor, Size size, Scalar mean, bool swapRB,

dnn_test.go

@@ -56,8 +56,27 @@ func checkNet(t *testing.T, net Net) {
 		t.Errorf("Invalid len layer names in ReadNet test: %d\n", len(lnames))
 	}
 
-	if len(lnames) == 142 && lnames[1] != "conv1/relu_7x7" {
-		t.Errorf("Invalid layer name in ReadNet test: %s\n", lnames[1])
+	m := map[int]string{
+		0:   "conv1/7x7_s2",
+		10:  "inception_3a/1x1",
+		20:  "inception_3a/pool",
+		30:  "inception_3b/5x5_reduce",
+		40:  "inception_4a/relu_1x1",
+		50:  "inception_4a/pool_proj",
+		60:  "inception_4b/relu_5x5_reduce",
+		70:  "inception_4c/relu_3x3_reduce",
+		80:  "inception_4c/output",
+		90:  "inception_4d/relu_5x5",
+		100: "inception_4e/relu_3x3",
+		110: "inception_5a/1x1",
+		120: "inception_5a/pool",
+		130: "inception_5b/5x5_reduce",
+		140: "loss3/classifier"}
+
+	for k, v := range m {
+		if lnames[k] != v {
+			t.Errorf("Invalid layer name in ReadNet test: \"%s\" (expected=\"%s\")\n", lnames[k], v)
+		}
 	}
 
 	prob := net.ForwardLayers([]string{"prob"})