fix potential out-of-border access in gpu StereoBeliefPropagation

modules/gpu/src/stereobp.cpp

@@ -213,8 +213,8 @@ namespace
 
             if (rthis.levels > 1)
             {
-                int less_rows = (rows + 1) / 2;
-                int less_cols = (cols + 1) / 2;
+                int less_rows = rows / 2;
+                int less_cols = cols / 2;
 
                 u2.create(less_rows * rthis.ndisp, less_cols, rthis.msg_type);
                 d2.create(less_rows * rthis.ndisp, less_cols, rthis.msg_type);
@@ -283,8 +283,8 @@ namespace
 
             for (int i = 1; i < rthis.levels; ++i)
             {
-                cols_all[i] = (cols_all[i-1] + 1) / 2;
-                rows_all[i] = (rows_all[i-1] + 1) / 2;
+                cols_all[i] = cols_all[i-1] / 2;
+                rows_all[i] = rows_all[i-1] / 2;
 
                 datas[i].create(rows_all[i] * rthis.ndisp, cols_all[i], rthis.msg_type);
 

modules/gpu/test/test_calib3d.cpp

@@ -114,7 +114,9 @@ GPU_TEST_P(StereoBeliefPropagation, Regression)
     cv::Mat h_disp(disp);
     h_disp.convertTo(h_disp, disp_gold.depth());
 
-    EXPECT_MAT_NEAR(disp_gold, h_disp, 0.0);
+    cv::Rect roi(0, 0, disp_gold.cols - 20, disp_gold.rows - 20);
+
+    EXPECT_MAT_NEAR(disp_gold(roi), h_disp(roi), 0.0);
 }
 
 INSTANTIATE_TEST_CASE_P(GPU_Calib3D, StereoBeliefPropagation, ALL_DEVICES);