The code is buggy. rax is used to store the original value of rsp and restore it at exit, but it’s also used as a temporary register in the loop in the middle of the function.
I suspect that this function was written manually in assembly but not actually tested on real hardware so the bug went unnoticed or, possibly, modified after initial testing and ...
The entry function you mentioned is the function where the entry point of the program is located. This entry function contains the first instructions of the program executed when you run the program.
The main function recognized by disassemblers is the the function where the main function of the program which code is compiled directly from the the developer'...
Main is usually a programmer-defined entry point, while entry is defined by the compiler, it's doing many other operations such as libc initializations, heap allocation, and so on, and eventually, call the user-defined main entry point. You can see main as a callback function that defined by the user and eventually called by entry.
Providing you know the length of the flag (obtain for example from RE) you can modify your code in the following way:
flag_chars = [claripy.BVS('flag_%d' % i, 8) for i in range(15)]
flag = claripy.Concat(*flag_chars+[claripy.BVV(b'\n')])
That will create an array with 15 (in this example) bit vectors of the size of 8-bits. And on the ...