c++ incorrect checksum for freed object- - c++

Question

I am getting this error (memory location varies between runs):
Freeing memory!
Image_Processing(6282,0x100091000) malloc: * error for object 0x1212121212121212: pointer being freed was not allocated
* set a breakpoint in malloc_error_break to debug
in this point it crashes : //delete m_data;
class Uint8Image {
public:
uint32_t m_w;
uint32_t m_h;
uint8_t *m_data;
Uint8Image(uint32_t w, uint32_t h): m_w(w), m_h(h), m_data(0)
{
m_data = new uint8_t(w*h);
}
Uint8Image(const Uint8Image &obj) ;
Uint8Image& operator = (const Uint8Image &D ) {
if(this != &D)
{
delete [] m_data;
m_w= D.m_w;
m_h = D.m_h;
m_data=new uint8_t(m_w * m_h); // deep copy the pointer data
}
return *this;
}
~Uint8Image()
{
std::cout << "Freeing memory!"<< std::endl;
delete m_data; // it crashes here
m_data = NULL;
}
};
class MeniscusFinderContext {
public:
MeniscusFinderContext( uint32_t m_a, uint32_t m_b):
{
m_input_image = new Uint8Image(m_a,m_b);
}
~MeniscusFinderContext()
{
delete m_input_image;
m_input_image = NULL;
}
Uint8Image m_input_image;};
//The function that calls:
// Taking input through option-parsing,
int main(int argc, char *argv[]{
const char *file_name = options[INPUT].arg;
std::ifstream file_stream(file_name,
std::ifstream::in | std::ifstream::binary);
char buf[256];
char *sEnd;
file_stream.getline(buf, sizeof(buf));
if(buf[0] != 'P' || buf[1] != '5') {
std::cerr << "invalid input PGM file" << std::endl;
return 1;
}
file_stream.getline(buf, sizeof(buf));
while(buf[0] == '#') file_stream.getline(buf, sizeof(buf));
uint32_t m_a = strtol(buf, &sEnd, 10);
uint32_t m_b = strtol(sEnd, &sEnd, 10);
MeniscusFinderContext M(m_a,m_b);
file_stream.getline(buf, sizeof(buf));
while(buf[0] == '#') file_stream.getline(buf, sizeof(buf));
if(atoi(buf) != 255) return 3;
file_stream.read((char *)M.m_input_image->m_data ,m_a * m_b);
if(!file_stream) {
std::cerr << "only got " << file_stream.gcount() << std::endl;
return 2;
}
file_stream.close();
return 0;
}
Edit: I'm running it and sometimes it runs while others it gives me the error. Seems to be at a random order. Any hints would be really helpful.
I already have checked all the related answers in stack overflow, but could nt figure it out.

Answer 1

new uint8_t(w*h);
This allocates exactly one uint8_t, whose initial value is w*h.
You probably intended:
new uint8_t[w*h];
Otherwise, this:
file_stream.read((char *)M.m_input_image->m_data ,m_a * m_b);
will immediately overrun this buffer. The same bug occurs several times in the shown code.
delete m_data;
Stuff allocated with new[] should be deallocated with delete[].
In general, your overall approach is very error-prone. Instead of manually handling memory, in this fashion, you should be using std::vector, and iterators. Correct usage of C++'s containers greatly reduces the possibility of making these kinds of bugs.