Addendum #1 to the fix for bug #16451878 : GEOMETRY QUERY CRASHES SERVER

Fixed the get_data_size() methods for multi-point features to check properly for end 
of their respective data arrays.
Extended the point checking function to take a 3d optional argument so cases where
there's additional data in each array element (besides the point data itself) can be
covered by the helper function.
Fixed the 3 cases where such offset was present to use the proper checking helper 
function.
Test cases added.
Fixed review comments.

sql/spatial.cc

@@ -395,19 +395,13 @@ const char *Geometry::get_mbr_for_points(MBR *mbr, const char *data,
 					 uint offset) const
 {
   uint32 points;
-  size_t points_available;
   /* read number of points */
   if (no_data(data, 4))
     return 0;
   points= uint4korr(data);
   data+= 4;
 
-  /* can't use any of the helper functions due to the offset */
-  points_available=
-    data <= m_data_end ? 
-    (m_data_end - data) / (POINT_DATA_SIZE + offset) : 0;
-
-  if (points_available < points)
+  if (not_enough_points(data, points, offset))
     return 0;
 
   /* Calculate MBR for points */
@@ -490,9 +484,16 @@ const Geometry::Class_info *Gis_point::get_class_info() const
 
 uint32 Gis_line_string::get_data_size() const 
 {
+  size_t n_points;
   if (no_data(m_data, 4))
     return GET_SIZE_ERROR;
-  return 4 + uint4korr(m_data) * POINT_DATA_SIZE;
+
+  n_points= uint4korr(m_data);
+
+  if (not_enough_points(m_data + 4, n_points))
+    return GET_SIZE_ERROR;
+
+  return 4 + n_points * POINT_DATA_SIZE;
 }
 
 
@@ -705,10 +706,18 @@ uint32 Gis_polygon::get_data_size() const
 
   while (n_linear_rings--)
   {
+    size_t n_points;
     if (no_data(data, 4))
       return GET_SIZE_ERROR;
-    data+= 4 + uint4korr(data)*POINT_DATA_SIZE;
+    n_points= uint4korr(data);
+    data+= 4;
+
+    if (not_enough_points(data, n_points))
+      return GET_SIZE_ERROR;
+
+    data+= n_points * POINT_DATA_SIZE;
   }
+
   return (uint32) (data - m_data);
 }
 
@@ -1038,9 +1047,17 @@ const Geometry::Class_info *Gis_polygon::get_class_info() const
 
 uint32 Gis_multi_point::get_data_size() const 
 {
+  size_t n_points;
+
   if (no_data(m_data, 4))
     return GET_SIZE_ERROR;
-  return 4 + uint4korr(m_data)*(POINT_DATA_SIZE + WKB_HEADER_SIZE);
+
+  n_points= uint4korr(m_data);
+
+  if (not_enough_points(m_data + 4, n_points, WKB_HEADER_SIZE))
+    return GET_SIZE_ERROR;
+
+  return 4 + n_points * (POINT_DATA_SIZE + WKB_HEADER_SIZE);
 }
 
 
@@ -1104,7 +1121,6 @@ uint Gis_multi_point::init_from_wkb(const char *wkb, uint len, wkbByteOrder bo,
 bool Gis_multi_point::get_data_as_wkt(String *txt, const char **end) const
 {
   uint32 n_points;
-  size_t points_available;
   const char *data= m_data;
 
   if (no_data(data, 4))
@@ -1112,13 +1128,11 @@ bool Gis_multi_point::get_data_as_wkt(String *txt, const char **end) const
 
   n_points= uint4korr(data);
   data+= 4;
-  points_available= data <= m_data_end ?
-    (m_data_end - data) / (POINT_DATA_SIZE + WKB_HEADER_SIZE) : 0;
 
-  /* can't use any of the helper functions due to WKB_HEADER_SIZE */
-  if (n_points > points_available ||
+  if (not_enough_points(data, n_points, WKB_HEADER_SIZE) ||
       txt->reserve(((MAX_DIGITS_IN_DOUBLE + 1) * 2 + 1) * n_points))
     return 1;
+
   *end= append_points(txt, n_points, data, WKB_HEADER_SIZE);
   txt->length(txt->length()-1);			// Remove end ','
   return 0;
@@ -1177,10 +1191,18 @@ uint32 Gis_multi_line_string::get_data_size() const
 
   while (n_line_strings--)
   {
+    size_t n_points;
+
     if (no_data(data, WKB_HEADER_SIZE + 4))
       return GET_SIZE_ERROR;
-    data+= (WKB_HEADER_SIZE + 4 + uint4korr(data + WKB_HEADER_SIZE) *
-	    POINT_DATA_SIZE);
+
+    n_points= uint4korr(data + WKB_HEADER_SIZE);
+    data+= WKB_HEADER_SIZE + 4;
+
+    if (not_enough_points(data, n_points))
+      return GET_SIZE_ERROR;
+
+    data+= n_points * POINT_DATA_SIZE;
   }
   return (uint32) (data - m_data);
 }
@@ -1432,9 +1454,16 @@ uint32 Gis_multi_polygon::get_data_size() const
 
     while (n_linear_rings--)
     {
+      size_t n_points;
       if (no_data(data, 4))
         return GET_SIZE_ERROR;
-      data+= 4 + uint4korr(data) * POINT_DATA_SIZE;
+      n_points= uint4korr(data);
+      data+= 4;
+
+      if (not_enough_points(data, n_points))
+        return GET_SIZE_ERROR;
+
+      data+= n_points * POINT_DATA_SIZE;
     }
   }
   return (uint32) (data - m_data);

sql/spatial.h

@@ -337,12 +337,15 @@ class Geometry
 
      @arg data              pointer to the begining of the points array
      @arg expected_points   number of points expected
+     @arg extra_point_space extra space for each point element in the array
      @return               true if there are not enough points
   */
-  inline bool not_enough_points(const char *data, uint32 expected_points) const
+  inline bool not_enough_points(const char *data, uint32 expected_points,
+                                uint32 extra_point_space = 0) const
   {
     return (m_data_end < data ||
-            (expected_points > ((m_data_end - data) / POINT_DATA_SIZE)));
+            (expected_points > ((m_data_end - data) /
+                                (POINT_DATA_SIZE + extra_point_space))));
   }
   const char *m_data;
   const char *m_data_end;