Question

I guess there is problem with the relation of malloc and goto. Or, I guess there is some wastage of memory or corruption of memory happening out here. Hope, someone can point to me the exact error.
When I compile its not giving me any error, but, my senior is insisting that I have a mistake.

#define FINISH() goto fini;

BOOL Do()
{

    BOOL stat;
    UINT32 ptr;
    int err;

    ptr = (UINT32)malloc(1000);


    free((void*)ptr);

fini:
    return stat;
}

Answer 1

Here are the problems I spotted in the code

• When err != ERROR_SUCCESS this function will leak memory. It will jump over the free call.
• You are storing the return of malloc into a 32 bit location. This is not a portable solution. On 64 bit platforms this will wreak havoc on your program as you’d be truncating the address. If you must use a non-pointer type here use size_t instead (although I would reccomend a pointer over an integral type)
• The local stat is not definitively assigned here. You are returning garbage if err != ERROR_SUCCESS. It needs to always be assigned a value. Easiest way is provide a default.
• You don’t check the return value of malloc and potentially pass a hidden NULL pointer into Fun2

Here’s the function with the edits I suggested

BOOL Do()
{

    BOOL stat = FALSE;
    size_t ptr = 0;
    int err;

    ptr = (UINT32)malloc(1000);
    err = Fun1();

    if (err != ERROR_SUCCESS || ptr == 0)
        FINISH();
    else
        stat = Fun2(ptr);

fini:
    free((void*)ptr);
    return stat;
}