Segmentation fault on ARM due to oversized Eigen matrix

[MariusHuber]

System

• Hardkernel Odroid XU4
• Ubuntu 14.04 LTS

Problem

Elevation mapping throws std::bad_alloc() as soon as the map is supposed to be moved. Adding point clouds to a map fixed in position works.

Where in the code the problem occurs

Using gdb leads to ElevationMap.cpp:286. At the core, the problem is that grid_map::EllipseIterator.cpp:32 is not initialized. This function is called by ElevationMap.cpp:285. Eigen allocates an immense amount of memory and finally throws std::bad_alloc() from Eigen/src/Core/util/Memory.h:362-367.

// Eigen/src/Core/util/Memory.h, lines 362 to 367
template<typename T>
EIGEN_ALWAYS_INLINE void check_size_for_overflow(size_t size)
{
  if(size > size_t(-1) / sizeof(T))
    throw_std_bad_alloc();
}

Hacky fix

A quick, hacky fix is to skip the map fusion process of a specific cell in case too much memory is allocated. This code is added between ElevationMap.cpp:285 and ElevationMap.cpp:286:

// If maxNumberOfCellsToFuse is too high, Eigen will throw a std::bad_alloc() error.
// Therefore, skip fusing in that case.
if (maxNumberOfCellsToFuse > (size_t(-1) / sizeof(float))) {
  // Skip fusing.
  fusedMap_.at("elevation", *areaIterator) = rawMapCopy.at("elevation", *areaIterator);
  fusedMap_.at("lower_bound", *areaIterator) = rawMapCopy.at("elevation", *areaIterator) - 2.0 * sqrt(rawMapCopy.at("variance", *areaIterator));
  fusedMap_.at("upper_bound", *areaIterator) = rawMapCopy.at("elevation", *areaIterator) + 2.0 * sqrt(rawMapCopy.at("variance", *areaIterator));
  fusedMap_.at("color", *areaIterator) = rawMapCopy.at("color", *areaIterator);
  continue;
}

This is only a temporary fix. The issue should be fixed more permanently in grid_map.

[MariusHuber]

@pfankhauser hope this helps.

[maximilianwulf]

Closing due to inactivity. Feel free to re-open.