How can I do a proof concept to show it?

Question

How can I do a proof concept to show it?

I Know it is 512 , and then if it's a multiple of 8 which translate to A*8*6*65 then it should crash, but dont
signed __int64 result; // rax

int msg; // [rsp+278h] [rbp-20h]

*(_QWORD *)v4 = -1i64;

v9 = 62;

memset(&Dst, 0, 0x200ui64);

if ( msg <= 512 )

size_data = recv(s, &Dst, (unsigned __int16)msg, 0);

if ( (signed int)size_data % 8 )