c++gccgcc8

stack smashing detected when no return statement in function returning non-void

I have been debugging a crash in a program which aborts with the error stack smashing detected. I have narrowed down the crash to just one function which is:

static ssize_t a (const char *x, const char *y, size_t z) {
#ifdef SOME_FLAG
    return b(x, y, z);
#endif
}

Since I am not defining SOME_FLAG anywhere, the function essentially does nothing and exits without a return statement.

I observed that if I just add a return 0 outside the #ifdef #endif block, the program doesn't abort (due to stack smash). The abort is also not seen if I define the function as static void instead of static ssize_t

Can the lack of a return statement cause stack-protector to trigger abort?

Solution

  • Regarding C++:

    If a function (other than main) declared to return a non-void value exists without return or throw, then the behaviour of the program is undefined.

    Can the lack of a return statement cause stack-protector to trigger abort?

    Yes. The behaviour is undefined. Anything can happen.