[kondbg]

This is a common way of executing shellcode in a PoC.

Exec (before the cast) points to memory containing the shellcode data.

To actually start executing the shellcode, you just need to somehow cause the program counter to point to the address of the shellcode.

An easy way to change the program counter is by calling a function ... which is what this line does.

Read this as "cast exec to a pointer to a function that takes zero arguments and returns void and call the function with no arguments."

This is the same as:

   typedef void (*some_func)();
   some_func func = (some_func)exec;
   func();

To familiarize yourself with C syntax regarding pointers, read about the "right-left rule" [1]

[1] http://ieng9.ucsd.edu/~cs30x/rt_lt.rule.html

[Uptrenda]

This is insanely clever. Thanks a lot for the explanation