Fix uninitialized memory disclosure in WASM CropAndResize

tfjs-backend-wasm/src/cc/kernels/CropAndResize.cc

@@ -16,6 +16,7 @@
 #include <emscripten.h>
 #endif
 
+#include <algorithm>
 #include <cmath>
 #include <cstddef>
 #include <cstring>
@@ -119,11 +120,15 @@ void CropAndResize(size_t images_id, size_t boxes_id, size_t box_ind_id,
     const float x2 = *boxes_buf;
     boxes_buf++;
 
-    if (*box_ind_buf >= batch) {
+    if (*box_ind_buf < 0 || static_cast<size_t>(*box_ind_buf) >= batch) {
+      float* out_buf_ptr = out_buf + b * output_strides[0];
+      std::fill(out_buf_ptr, out_buf_ptr + output_strides[0], 0.0f);
+      box_ind_buf++;
       continue;
     }
 
-    const size_t box_offset = *box_ind_buf * images_strides[0];
+    const size_t box_offset =
+        static_cast<size_t>(*box_ind_buf) * images_strides[0];
 
     const float height_scale =
         (crop_height > 1) ? (y2 - y1) * image_height_m1 / (crop_height - 1) : 0;

tfjs-backend-wasm/src/index_test.ts

@@ -65,6 +65,26 @@ describeWithFlags('wasm read/write', ALL_ENVS, () => {
     test_util.expectArraysClose(await t.data(), view);
   });
 
+  it('cropAndResize zero-fills out-of-range box indices', async () => {
+    const image = tf.tensor4d([1, 2, 3, 4], [1, 2, 2, 1]);
+    const boxes = tf.tensor2d([
+      0, 0, 1, 1,
+      0, 0, 1, 1,
+    ], [2, 4]);
+    const boxInd = tf.tensor1d([999, -1], 'int32');
+
+    const output =
+        tf.image.cropAndResize(image, boxes, boxInd, [4, 4], 'nearest', -7);
+
+    expect(output.shape).toEqual([2, 4, 4, 1]);
+    test_util.expectArraysClose(await output.data(), new Float32Array(32));
+
+    image.dispose();
+    boxes.dispose();
+    boxInd.dispose();
+    output.dispose();
+  });
+
   // TODO(mattSoulanille): Re-enable this once it's working on iOS.
   // tslint:disable-next-line: ban
   xit('allocates more than two gigabytes', async () => {