[mlpack-git] master: Fixed an error in MidpointSplit that may lead to a segfault (a659b90)

[gitdub at mlpack.org]

Repository : https://github.com/mlpack/mlpack
On branch  : master
Link       : https://github.com/mlpack/mlpack/compare/3a1bc90ea5f1ffa45d2de000efb4429c60468b21...ef51b032f275266f781d42b9bd0aa50aa26a3077

>---------------------------------------------------------------

commit a659b90e57931d0377167cb980602ed565b44536
Author: Mikhail Lozhnikov <lozhnikovma at gmail.com>
Date:   Wed Jul 27 18:00:28 2016 +0300

    Fixed an error in MidpointSplit that may lead to a segfault


>---------------------------------------------------------------

a659b90e57931d0377167cb980602ed565b44536
 .../tree/binary_space_tree/midpoint_split_impl.hpp | 28 ++++++++++++++++------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/src/mlpack/core/tree/binary_space_tree/midpoint_split_impl.hpp b/src/mlpack/core/tree/binary_space_tree/midpoint_split_impl.hpp
index 70ec94d..1aa16b3 100644
--- a/src/mlpack/core/tree/binary_space_tree/midpoint_split_impl.hpp
+++ b/src/mlpack/core/tree/binary_space_tree/midpoint_split_impl.hpp
@@ -24,6 +24,7 @@ bool MidpointSplit<BoundType, MatType>::SplitNode(const BoundType& bound,
 {
   size_t splitDimension = data.n_rows; // Indicate invalid.
   double maxWidth = -1;
+  double splitVal = DBL_MAX;
 
   // Find the split dimension.  If the bound is tight, we only need to consult
   // the bound's width.
@@ -37,6 +38,9 @@ bool MidpointSplit<BoundType, MatType>::SplitNode(const BoundType& bound,
       {
         maxWidth = width;
         splitDimension = d;
+
+        // Split in the midpoint of that dimension.
+        splitVal = bound[d].Mid();
       }
     }
   }
@@ -65,18 +69,20 @@ bool MidpointSplit<BoundType, MatType>::SplitNode(const BoundType& bound,
       {
         maxWidth = width;
         splitDimension = d;
+
+        // Split in the midpoint of that dimension.
+        splitVal = ranges[d].Mid();
       }
     }
 
     delete[] ranges;
   }
 
+  assert(splitVal != DBL_MAX);
+
   if (maxWidth == 0) // All these points are the same.  We can't split.
     return false;
 
-  // Split in the midpoint of that dimension.
-  double splitVal = bound[splitDimension].Mid();
-
   // Perform the actual splitting.  This will order the dataset such that points
   // with value in dimension splitDimension less than or equal to splitVal are
   // on the left of splitCol, and points with value in dimension splitDimension
@@ -96,6 +102,7 @@ bool MidpointSplit<BoundType, MatType>::SplitNode(const BoundType& bound,
 {
   size_t splitDimension = data.n_rows; // Indicate invalid.
   double maxWidth = -1;
+  double splitVal = DBL_MAX;
 
   // Find the split dimension.  If the bound is tight, we only need to consult
   // the bound's width.
@@ -109,6 +116,9 @@ bool MidpointSplit<BoundType, MatType>::SplitNode(const BoundType& bound,
       {
         maxWidth = width;
         splitDimension = d;
+
+        // Split in the midpoint of that dimension.
+        splitVal = bound[d].Mid();
       }
     }
   }
@@ -132,22 +142,26 @@ bool MidpointSplit<BoundType, MatType>::SplitNode(const BoundType& bound,
     // Now, which is the widest?
     for (size_t d = 0; d < data.n_rows; d++)
     {
-      const double width = bound[d].Width();
+      const double width = ranges[d].Width();
 
       if (width > maxWidth)
       {
         maxWidth = width;
         splitDimension = d;
+
+        // Split in the midpoint of that dimension.
+        splitVal = ranges[d].Mid();
       }
     }
+
+    delete[] ranges;
   }
 
+  assert(splitVal != DBL_MAX);
+
   if (maxWidth == 0) // All these points are the same.  We can't split.
     return false;
 
-  // Split in the midpoint of that dimension.
-  double splitVal = bound[splitDimension].Mid();
-
   // Perform the actual splitting.  This will order the dataset such that points
   // with value in dimension splitDimension less than or equal to splitVal are
   // on the left of splitCol, and points with value in dimension splitDimension