I want to cause a buffer overflow to call a function
Hello!
I tried to cause a buffer overflow, and i need some expert here.
I want to call the "callme" function in the little program i've written below:
Code:
#include "stdio.h"
#include "stdlib.h"
void io(void);
void callme(void);
int main() {
io();
return 0;
}
void io(void) {
char input[16];
printf("input:\n");
scanf("%s", input);
printf("%s\n", input);
}
void callme(void) {
printf("you made it!\n");
}
Okay now, what i want is to redirect the flow:
from main to io()
from io() instead of return to main() i want to go to callme(), and then i dont care anymore.
with gdb i found out that the callme address should be:
0x4013db
40 13 db
-> to little endian
db 13 40
-> to decimal
219 19 64
-> to ascii
Û @
okay, now I am not sure where to enter this, when receiving an input, it crashes when i put in 24 characters. 23 is okay. But does that mean my return address is stored at the 24th? Probably not.
i tried input values like:
abcdefghijklmnopqrstuvwÛ @
but the program simply crashed, and
abcdefghijklmnopqrstuvÛ @
just did nothing, it printed it again.
I'm still a beginner in this field, I'm happy with any advice! Even if I'm terribly wrong with what I did so far!
