为什么这个C代码产生双重免费或损坏？

Question

为什么这个用于计算两个向量的内积的代码产生双重释放或损坏错误,当编译时:

ejspeiro@Eduardo-Alienware-14:~/Dropbox/HPC-Practices$ gcc --version
gcc (Ubuntu 4.8.4-2ubuntu1~14.04) 4.8.4

代码来自此参考.

// Computation of the inner product of vectors aa and bb.

#include <stdio.h>
#include <stdlib.h>

int main() {

  size_t nn = 100000000;
  size_t total_mem_array = nn*sizeof(double);

  double *aa;
  double *bb;
  double ss = 0.0;

  aa = (double *) malloc(total_mem_array);
  bb = (double *) malloc(total_mem_array);

  int ii = 0;

  for (ii = 0; ii < nn; ++ii) {
    aa[ii] = 1.0;
    bb[ii] = 1.0;
  }

  double sum1 = 0.0;
  double sum2 = 0.0;

  for (ii = 0; ii < nn/2 - 1; ++ii) {
    sum1 += (*(aa + 0))*(*(bb + 0));
    sum2 += (*(aa + 1))*(*(bb + 1));
    aa += 2;
    bb += 2;
  }
  ss = sum1 + sum2;

  free(aa);
  free(bb);

  return 0;
}

Answer 1

导致错误是因为传递给的值free()与返回的值不同malloc(),因为您递增aa和bb.

例如,为了纠正它,您可以定义两个仅用于内存管理的附加指针变量,即分配和释放.一旦他们获得了内存,就将其分配给aa和bb.