Find the bug

gistfile1.c

/*
 * -( nemo2.c )-
 *
 *  2015
 *
 */

#include <stdio.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <openssl/sha.h>

//0000000: 9090 9090 9090 9090 9090 9090 9090 9090  ................
//0000010: 9090 9090 c30a                           ......

#define DAHASH "dff3f88ce2a59972f0c84a4d730519ebfd591f9d0d4bfeb6970f1114a217c1fe"

int main(int ac, char **av)
{
	int i,fd;
        long *mapped;
	void (*fp)();
	char md[SHA256_DIGEST_LENGTH];
	char ascii_hash[SHA256_DIGEST_LENGTH * 2];

	if(ac != 2) {
		printf("usage: %s <shellcode file>\n",av[0]);
		exit(1);
	}

        if((fd = open(av[1],O_RDONLY)) == -1) {
                printf("[!] error: failed to open\n");
                exit(1);
        }

	if((mapped = mmap(NULL, 0x1000, PROT_READ|PROT_EXEC, MAP_SHARED, fd, 0)) == -1) {
                printf("[!] error: mmap failed\n");
                exit(1);
        }

	if(!SHA256(mapped, 0x1000,&md)) {
		printf("[!] error: could not create SHA256\n");
		exit(1);
	}
	
	for(i = 0; i < SHA256_DIGEST_LENGTH; i++) {
		sprintf(&ascii_hash[i*2],"%02x", (unsigned char)md[i]);
	}
	printf("[+] Hash of input: %s\n",ascii_hash);

	if(strcmp(ascii_hash, DAHASH)) {
		printf("[!] error: hash did not match\n");
		exit(1);
	}

	printf("[+] Match, executing payload\n");
	fp = mapped;
	fp();
	
}