免费无效指针错误

Question

我有以下for循环：

for (size_t matchIdx = 0; matchIdx < matcherTypes.size(); matchIdx++)
{
  std::vector< DMatchVector > matches12;
  std::vector< DMatchVector > matches21;
  try
  {
    poi.knnMatch(descriptorsInterior, descriptorsCar, cfg.getPOIMatchKNN(),
                 matcherTypes[matchIdx], matches21);
    poi.knnMatch(descriptorsCar, descriptorsInterior, cfg.getPOIMatchKNN(),
                 matcherTypes[matchIdx], matches12);
  }
  catch (MyPOIException& mpoie)
  {
    std::cerr << mpoie.what() << std::endl;
  }

  DMatchVector matches;
  filterDMatch(matches12, matches21, matches);

  ElectPOI elPOI;
  std::vector< size_t > cntrVec(matches.size(), 0);
  elPOI.counterPOIs(matches, cntrVec);

  KeyPointVector filteredKPs;
  elPOI.thresholdKeyPoints(1, kpInteriorVec, cntrVec, filteredKPs);

  std::cout << "keypoints found:   " << kpInteriorVec.size() << std::endl
            << "keypoints matched: " << matches.size() << std::endl;


  cv::Mat tmpMat;
  cv::drawKeypoints(interiorImage, filteredKPs, tmpMat);
  cv::imshow("filtered keypoints", tmpMat);
  cv::waitKey();

} // for each matcher type

我没有指针，除了Ptr knnMatch(...)方法中的OpenCV poi（在for循环之外定义）：

void POI::knnMatch(const cv::Mat& queryDescriptorsIn, const cv::Mat& trainDescriptorsIn,
                   int knnIn, const std::string& matcherTypeIn,
                   std::vector< DMatchVector >& matchesOut)
{
  std::vector<DMatchVector> result;

  cv::Ptr< cv::DescriptorMatcher > descriptorMatcher
                                          = cv::DescriptorMatcher::create(matcherTypeIn);
  if (descriptorMatcher.empty())
  {
    std::string msg = "Matcher of type " + matcherTypeIn + " was not created!";
    throw MyPOIException(msg);
  }
  descriptorMatcher->knnMatch(queryDescriptorsIn, trainDescriptorsIn, result, knnIn);

  matchesOut = result;
}

我不明白为什么它会因以下错误而崩溃：

*** Error in `/home/me/projects/prj/build/prj': free(): invalid pointer: 0x000000000110dda2 ***

实际上，在显示图像之前，它会在循环的每个第二步崩溃。任何sugestions？我做错了什么？

---

修改

Valgrind说：

==10329== Invalid read of size 8
==10329==    at 0x605479: ElectPOI::counterPOIs(std::vector<cv::DMatch, std::allocator<cv::DMatch> > const&, std::vector<unsigned long, std::allocator<unsigned long> >&) (CElectPOI.cpp:12)
==10329==    by 0x5D8A87: main (main.cpp:199)
==10329==  Address 0xc74ec60 is not stack'd, malloc'd or (recently) free'd

valgrind: m_mallocfree.c:303 (get_bszB_as_is): Assertion 'bszB_lo == bszB_hi' failed.
valgrind: Heap block lo/hi size mismatch: lo = 449, hi = 450.
This is probably caused by your program erroneously writing past the
end of a heap block and corrupting heap metadata.  If you fix any
invalid writes reported by Memcheck, this assertion failure will
probably go away.  Please try that before reporting this as a bug.

功能如下：

void ElectPOI::counterPOIs(const DMatchVector& matchesIn, std::vector< size_t >& cntrVecInOut)
{
  for (size_t i = 0; i < matchesIn.size(); i++)
  {
    int qryIdx = matchesIn[i].queryIdx;    
    cntrVecInOut[qryIdx]++;  // line 12
  }
}