Realloc "random" crash

Realloc "random" crash

I have this function to read a triangular 2d array, but sometimes it
crashes on realloc. Always on the 6th realloc (current_row = 7). Sometimes
it runs fine. Cannot reproduce the error in gdb (works every time). What's
wrong?
TRIANGLE *read_triangle(char *file_name)
{
std::ifstream fin(file_name);
int current_row = 0, current_column = 0, buffer;
TRIANGLE *triangle = new TRIANGLE();
triangle->triangle_values[0] = new int[1];
while (fin >> buffer)
{
if (current_column == current_row+1)
{
current_column = 0;
triangle->triangle_values =
(int**)realloc(&((void*)triangle->triangle_values),
(++current_row+1)*sizeof(int*));
triangle->triangle_values[current_row] = new int[current_row];
}
triangle->triangle_values[current_row][current_column++] = buffer;
}
triangle->rows = current_row-1;
return triangle;
}